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  • 1.
    Aaboen, Lise
    NTNU, Trondheim.
    BATON-CHANGING ON EGGSHELLS – TRANSFERRING SUPPLIER RELATIONSHIPS WHEN MOVING PRODUCTION2014Conference paper (Refereed)
    Abstract [en]

    Production transfers are a result of outsourcing and offshoring decisions. Though, because of

    the strategic focus of the outsourcing literature have not the operational issues of how

    relationship development between sender, receiver and raw material been fully depicted. The

    purpose of the present paper is to explore relationship development connected to transfer of

    raw material supplies responsibility during transfer of production. To fulfil the purpose, four

    different production transfers were studied: three from Sweden to China, Romania and

    Hungary respectively and one transfer from Holland to Sweden. We can see that the

    dependence and power shifts gradually between the sender and the receiver and the

    relationship between them sets the arena for what relationship is developed between the

    receiver and the raw material suppliers. Furthermore, short social distances can over bridge

    cultural and technological distances to some extent, because it motivates to take the

    relationship into a more developed state.

  • 2.
    Aaboen, Lise
    et al.
    Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Fredriksson, Anna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The relationship development aspect of production transfer2016In: Journal of Purchasing and Supply Management, ISSN 1478-4092, E-ISSN 1873-6505, Vol. 22, no 1, p. 53-65Article in journal (Refereed)
    Abstract [en]

    Production transfers are a result of outsourcing and offshoring decisions. Because of the strategic focus of the outsourcing literature, the operational issues of relationship development between sender and receiver and its impact on the transfer progress have not been fully depicted. The purpose of the present paper is to explore relationship development during production transfer. To fulfil this purpose, we studied three different production transfers and derived four propositions for further testing. Our main conclusions included that dependence and power gradually shift between the sender and the receiver and that the relationship between them sets the arena for what types of relationships can be developed between the receiver and the suppliers. Furthermore, short social distances can bridge cultural and technological distances to some extent, because it motivates the actors to bring their relationship into a more developed state. Finally, we noticed that the headquarters’ involvement can work both as an inhibitor as well as a converter.

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  • 3.
    Aban, Kevin
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Göst, Jens
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Analysis of transports with pharmaceuticals on Arlanda airport2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Rapporten syftar till att kartlägga och analysera dagens transportflöde av läkemedel på fraktområdet Cargo City på Arlanda. Cargo Center och APH Logistics är två fraktagenter som har sin verksamhet på Cargo City. Observera att Cargo City och Cargo Center inte har samma innebörd. Cargo Center och APH Logistics erbjuder genom nära samarbete transport och hantering av temperaturkänsligt gods, som till exempel läkemedel. Läkemedel är värdefullt gods som kräver särskild skötsel vid transport, hantering och förvaring. Det ställer stränga krav på samtliga aktörer i försörjningskedjan. Genom studiebesök och intervjuer har författarna kartlagt det befintliga flödet av läkemedel. SACT, ett åkeri och dotterbolag till Cargo Center, utför transporten av godset till Cargo City med nerkylda lastbilar. APH Logistics omlastningsterminal på Cargo City är temperaturkontrollerad, vilket innebär att läkemedelsgodset förvaras och lastats i flygcontainrar där. Det färdiglastade godset forslas sedan vidare till Cargo Centers terminal. Där sker vikt- och volymkontroll av godset, det registreras i olika datasystem och slutligen märks det med etiketter, så som flygfraktsedeln. Mycket av godset som hanteras på Arlanda körs med lastbil till andra flygplatser och destinationer runt om i Europa istället för att flygfraktas direkt från flygplatsen. Dessutom hanteras och förvaras inte allt läkemedelsgods under temperaturkontrollerade former. En totalkostnadsanalys har gjorts för att jämföra olika transportflödesscenarion. Dessutom har författarna identifierat den kundservice Cargo Center och APH Logistics bör erbjuda kunden. Den bygger på kvalitativa resonemang. Resultatet av rapporten är författarnas rekommendation till företagen av hur de bör gå tillväga i framtiden. Den ger både kortsiktiga och långsiktiga tips.

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  • 4.
    Abdella, Juhar Ahmed
    et al.
    UAEU, U Arab Emirates.
    Zaki, N. M.
    UAEU, U Arab Emirates.
    Shuaib, Khaled
    UAEU, U Arab Emirates.
    Khan, Fahad
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering.
    Airline ticket price and demand prediction: A survey2021In: Journal of King Saud University - Computer and Information Sciences, ISSN 1319-1578, Vol. 33, no 4, p. 375-391Article in journal (Refereed)
    Abstract [en]

    Nowadays, airline ticket prices can vary dynamically and significantly for the same flight, even for nearby seats within the same cabin. Customers are seeking to get the lowest price while airlines are trying to keep their overall revenue as high as possible and maximize their profit. Airlines use various kinds of computational techniques to increase their revenue such as demand prediction and price discrimination. From the customer side, two kinds of models are proposed by different researchers to save money for customers: models that predict the optimal time to buy a ticket and models that predict the minimum ticket price. In this paper, we present a review of customer side and airlines side prediction models. Our review analysis shows that models on both sides rely on limited set of features such as historical ticket price data, ticket purchase date and departure date. Features extracted from external factors such as social media data and search engine query are not considered. Therefore, we introduce and discuss the concept of using social media data for ticket/demand prediction. (c) 2019 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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  • 5.
    Abrahamsson, Mats
    Linköping University, Department of Management and Engineering, Logistics & Quality Management. Linköping University, Faculty of Science & Engineering.
    Logistik för ökad svensk konkurrenskraft: Forsknings- och innovationsagenda för framtidens logistik2013Report (Other academic)
    Abstract [sv]

    Framtidens logistik står inför mycket stora utmaningar som har direkt bäring på svenska företags och organisationers förmåga till tillväxt, hållbarhet och konkurrenskraft. 

    Det står utom all tvivel att logistikens betydelse kommer att öka ännu mer i framtiden. Vinnare på de globala, rörliga marknaderna kommer ett vara de flödeseffektiva företagen, som har förmåga att hantera förändringarna på marknaden med en effektiv logistik som grund. För att lyckas behövs ett Logistiklyft för Sverige, med ett medvetet fokus på att utveckla de dynamiska förmågorna i företag och organisationer. Detta gäller i de allra flesta branscher och typ av företag.

    Den här innovations- och forskningsagendan utgår från den svenska traditionen och internationellt sett unika kunskapen och förmågan att med en systemsyn som grund designa, utveckla och styra komplexa system där flera olika kompetenser samverkar. Logistikens systemkunskap handlar om att lära sig att utforma och styra omfattande och allt mer komplexa försörjningskedjor (supply chains) från råvara till slutkund i syfte att öka svenska företags internationella konkurrenskraft och förmåga att växa på ett miljömässigt och ekonomiskt hållbart sätt

    Agendan adresserar behovet av kompetens och kunskap för mer innovativ logistikutveckling som följer:

    • Utveckling av kunskap om nya och mer innovativa logistiksystem och modeller för industri & handel 
    • Tjänsteutveckling för transport/logistik och IT-företag som stöd för mer innovativa logistiksystem, men också att ta till vara och stimulera den omfattande tjänsteutveckling som finns i förnyelsen av svenskt näringsliv, t ex mot högre grad av e-handel. 
    • Tillämpning av befintliga logistikkunskaper för områden och sektorer i behov av ett logistiklyft och ökad flödeseffektivitet, t.ex. logistik för små- och medelstora företag (SME) med fokus på HUR (genomförandeprocesser) istället för VAD (utformning av koncept och modeller). 
    • Utveckling av kunskaper om hur logistiksystem kan bidra till en hållbar utveckling, såväl miljömässigt som socialt.
    • Utveckling av kunskap om och tillämpning av logistiklösningar med primär samhällsnytta, t ex sjukvårdslogistik och citylogistik samt effektiv och hållbar försörjning av livsmedel, energi etc.

    Den här forsknigs- och innovationsagendan är utvecklad i samarbete mellan Linköpings Universitet, Lunds Tekniska Högskola, Chalmers Tekniska Högskola och en lång rad företag där Axis, SKF, Volvo och Nobel Biocare har funnits med i projektets styrgrupp. 

    Agendan finns endast som PDF. Kontakta Mats Abrahamsson, Linköpings Universitet. mats.abrahamsson@liu.se

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    Logistik för ökad svensk konkurrenskraft
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  • 6.
    Abrishami, Mahdi
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Dynamic Link Flow Estimation according to Historical Travel Times2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vast application of ITS and the availability of numerous on-road detection devices has resulted in variety of alternative data sources to be exploited and used in the field of traffic modelling. In this thesis, historical travel times, as an alternative data source, is employed on the developed method to perform dynamic network loading. The developed method, referred to as DNLTT, uses the share of each route available in the route choice set from the initial demand, as well as link travel times to perform the network loading. The output of the algorithm is time-dependent link flows. DNLTT is applied on Stockholm transportation network, where it is expected to have variation in link travel times in different time-periods, due to network congestion. In order to calculate the route shares, a time-sliced OD matrix is used. The historical travel times and the routes in the route choice set are extracted from an existing route planning tool. An available logit model, which considers the route travel time as the only logit parameter, is used for the route share calculation and the network loading is performed according to 2 different methods of DNLTT and DL. The evaluation of results is done for a toy network, where there happen different network states in different time-periods. Furthermore, the model output from Stockholm case study is analyzed and evaluated. The dynamic behavior of DNLTT is studied by analysis of link flows in different time-periods. Furthermore, the resulting link flows from both network loading methods are compared against observed link flows from radar sensors and the statistical analysis of link flows is performed accordingly. DNLTT exhibits a better performance on the toy network compared to DL, where the increasing link travel times cause the link flows to decline in different time-periods. However, the output of the developed method does not resemble the observed link flows for the investigated links in Stockholm case study. It is strongly believed, that the performance of DNLTT on the investigated transportation network potentially improves, in case the historical travel times better resemble the network dynamics. In addition to a more reliable data set, an OD adjustment process in all the time-periods is believed to generate better model output.

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    Dynamic Link Flow Estimation according to Historical Travel Times
  • 7.
    Adedokun, Adeyemi
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Application of Road Infrastructure Safety Assessment Methods at Intersections2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traffic safety at intersections is a particularly difficult phenomenon to study, given the fact that accidents occur randomly in time and space thereby making short-term measurement, assessment and comparison difficult. The EU directive 2008/96/EC introduced road infrastructure safety management, which offers a five layer structure for developing safer road infrastructure has been used to develop tools for accident prediction and black spot management analysis which has been applied in this work to assess the safety level of intersections in Norrköping city in Sweden. Accident data history from STRADA (Swedish Traffic Accident Data Acquisition) and the network demand model for Norrköping city were used to model black spots and predict the expected number of accidents at intersections using PTV Visum Safety tool, after STRADA accident classification was restructured and the Swedish accident prediction model (APM) was configured and tested to work within the tool using the model from the Swedish road administration (SRA). The performance of the default (Swiss) and the Swedish APM was compared and identified locations with the high accident records, predicted accident counts and traffic volumes were audited using qualitative assessment checklist from Street-Audit tool. The results from these methods were analysed, validated and compared. This work provides recommendations on the used quantitative and qualitative methods to prevent accident occurrence at the identified locations.

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  • 8.
    Adelsköld, Astrid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Review of general demand responsive transport in Sörmland county2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sörmlands län består till stor del av landsbygd där en kostnadseffektiv kollektivtrafik är svår att uppnå eftersom resandeunderlaget och därmed även efterfrågan normalt är låg. I dessa områden finns dock potential att uppnå en hållbar kollektivtrafik med hjälp av anropsstyrda trafikformer. I detta projekt utreddes dels en övergång av turer i landsbygdslinjetrafiken till allmän anropsstyrd trafik och dels en samordning av den allmänna och särskilda anropsstyrda kollektivtrafiken. En generell metod för val mellan fast linjetrafik och anropsstyrd linjelagd trafik utvecklades, vilken bestod av enkla tumregler för utvärdering av turer med regelbundet låg efterfrågan i landsbygdslinjetrafiken. Samordningen bestod av att utreda effekterna av att kompletteringsresor planerades och utfördes med samma fordon som den särskilda anropsstyrda kollektivtrafiken. Då kompletteringstrafiken får en högre kostnadseffektivitet genom samordning med den särskilda kollektivtrafiken kan denna användas som en flexibel ersättning där turutbudet i landsbygdslinjetrafiken behöver minska. En kostnadseffektivisering av landsbygdslinjetrafiken där turutbudet anpassas bättre till efterfrågan tillåter därmed en satsning av resurser till kompletteringstrafiken. Detta för att i enlighet med kollektivtrafikmyndighetens mål skapa en attraktiv kollektivtrafik för hållbar tillväxt och utveckling i Sörmlands län.

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  • 9.
    Adolfsson, Lovisa
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Nilsson, Rebecca
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Collection structure design of deposited PET bottles and aluminium cans in northern Sweden2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Returpack är ansvariga för Sveriges retursystem av tomma PET-flaskor och aluminiumburkar där insamling och hantering av förpackningar är en stor del av verksamheten. Transport av tomma förpackningar från butik till Returpacks fabrik i Norrköping sker huvudsakligen i form av lösvikt (bulklast) av Returpack. Övriga transporter av förpackningar sker i kartong eller säck där dryckesleverantörer sköter insamlingen. Syftet med denna studie är att skapa och undersöka olika typer av inhämtningsstrukturer för tomma förpackningar, där Returpack strävar efter att på ett kostnadseffektivt och miljömässigt sätt sköta inhämtningen samt öka kontrollen över flödet. I studien kommer fem områden i norra Sverige att undersökas, vilka skiljer sig från övriga områden i Sverige då dessa kännetecknas av långa avstånd mellan butiker samt låga volymer av förpackningar. I studien utförs ruttplanering av lösviktsinsamling samt totalkostnadberäkningar för varje område, där ett antal scenarier skapats med olika typer av inhämtningsstrukturer. I scenarierna varieras antalet butiker, mellanlager, ruttider samt insamlingsbilar. Utöver detta undersöks även fyra olika hubblösningar där förpackningarna gör en övergång från kartong- och säckflödet till lösviktsflödet. Resultaten av ruttplanerningarna visar att två av områdena har en hög belastning där antalet insamlingsbilar behöver ökas. Totalkostnadsberäkningarna tyder på att det går att sänka totalkostnaden i två av områdena genom att öka lösviktsinsamlingen. I de övriga tre områdena ger den nuvarande strukturen den lägsta totalkostnaden. Resultaten visar också att antalet fordonskilometer kan minska genom att addera ytterligare ett mellanlager i två av områdena. I studien visas det också att hubbar kan sänka kostnader för Returpack och minska antalet inkommande kartonger och säckar till fabriken. Att införa hubbar minskar också antalet fordonskilometer med mer än 50 %.

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    Collection structure design of deposited PET bottles and aluminium cans in northern Sweden
  • 10.
    Aghighi, Meysam
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Bäckström, Christer
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Cost-optimal and Net-benefit Planning: A Parameterised Complexity View2015In: 24th International Joint Conference on Artificial Intelligence (IJCAI-15), IJCAI-INT JOINT CONF ARTIF INTELL, ALBERT-LUDWIGS UNIV FREIBURG GEORGES-KOHLER-ALLEE, INST INFORMATIK, GEB 052, FREIBURG, D-79110, GERMANY , 2015, p. 1487-1493Conference paper (Refereed)
    Abstract [en]

    Cost-optimal planning (COP) uses action costs and asks for a minimum-cost plan. It is sometimes assumed that there is no harm in using actions with zero cost or rational cost. Classical complexity analysis does not contradict this assumption; planning is PSPACE-complete regardless of whether action costs are positive or non-negative, integer or rational. We thus apply parameterised complexity analysis to shed more light on this issue. Our main results are the following. COP is W[2]-complete for positive integer costs, i.e. it is no harder than finding a minimum-length plan, but it is para-NPhard if the costs are non-negative integers or positive rationals. This is a very strong indication that the latter cases are substantially harder. Net-benefit planning (NBP) additionally assigns goal utilities and asks for a plan with maximum difference between its utility and its cost. NBP is para-NP-hard even when action costs and utilities are positive integers, suggesting that it is harder than COP. In addition, we also analyse a large number of subclasses, using both the PUBS restrictions and restricting the number of preconditions and effects.

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  • 11.
    Ahlberg, John
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Cruz Wolter Håkansson, Christoffer
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Identification, mapping and control of non-structure-bound materials2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    I Saab Aerostructures tillverkning av flygplansdelar, används icke strukturbundet material, det vill säga material som inte har en angiven kvantifierad förbrukning per tillverkad enhet eller material vars angivna kvantifierade förbrukning per tillverkad enhet inte stämmer överens med verklig förbrukning. Personal på inköpsavdelningen vet i vissa fall inte var ett specifikt icke strukturbundet material förbrukas, alltså vilka tillverkningsavdelningar eller flygplansdelar som förbrukar materialet. Likaså saknas övergripande och gemensamma rutiner för hur material som klassas som icke strukturbundet material planeras och lagerstyrs. För att identifiera problemområden i materialförsörjningen genomfördes en flödeskartläggning för att identifiera vilka olika typer av icke strukturbundet material som används i Saab Aerostructures produktion samt hur dessa lagerstyrs mellan lager och buffertlager i produktion. Under flödeskartläggningen definierades sex olika materialgrupper tillhörande icke strukturbundet material. För att lagerstyra de identifierade materialgrupperna av icke strukturbundet material används idag åtta stycken lagerstyrningsmetoder. Saab Aerostructures har anlitat tredjepartslogistiker för att sköta merparten av dagens lagerstyrning. Lagerstyrningsmetoderna skiljer sig åt beroende på tredjepartslogistiker och materialgrupp av icke strukturbundet material. Resultatet från genomförd kartläggning och analys påvisar att det finns förbättringspotential i flera utav dessa lagerstyrningsmetoder, samt att det är möjligt att reducera antalet lagerstyrningsmetoder genom att använda samma lagerstyrningsmetod för snarlika materialgrupper av icke strukturbundet material. Genomförd analys påvisar även behovet av ett förbättrat informationsflöde mellan beredning, inköp och produktion, när det gäller hanteringen av icke strukturbundet material. Konkreta åtgärder i form av rekommendationer, för att förbättra lagerstyrningen av icke strukturbundet material, presenteras i slutet av denna rapport.  

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  • 12.
    Ahlepil, Erik
    et al.
    Linköping University, Department of Management and Engineering, Logistics & Quality Management.
    Björck, Joel
    Linköping University, Department of Management and Engineering, Logistics & Quality Management.
    Evaluating Distribution Structures for Overseas Export of Frozen Food.2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The meat producers of the western world needs to develop their export organizations and to streamline their physical distribution in order to take new market shares on the fast growing overseas markets. HKScan is one of those meat producing companies, the group has businesses in Finland, Sweden, Denmark and the Baltic countries. A part of their sales goes frozen on overseas export by container sea freight. Lately the logistics management of HKScan has been interested in investigating the effects of centralizing the physical distribution for the overseas export from Sweden and Denmark. This leads to the purpose of this study, which is:

     “For HKScan, develop and apply a model that evaluates distribution structures for overseas export of frozen food regarding total cost, delivery service, environmental impact and regulations.”

    The case study included comparison between the current distribution structure for HKScan and three pre-determined scenarios. The current setup consists of multiple warehouses in both countries. In the first scenario the distribution structure is centralized to include one warehouse per country. In the second scenario, the total export flow of products from both Sweden and Denmark is redirected and centralized to one warehouse in Denmark. In the third scenario, the total export flow of products from both Sweden and Denmark is instead redirected and centralized to one warehouse in Sweden.

    To evaluate and compare the different distribution structures a general model was first created by combining different theoretical models and adapting them to the context of overseas distribution for frozen food. The study then included the three phases of developing the model to fit the case company, applying the model on the case company and then to finally evaluating the model.

    The resulting model, which was the outcome of the development process, can be seen below. The model illustrates the different included elements.

    By then applying the model onto the case company, HKScan, it was found that a centralization to a joint warehouse in Denmark would make total cost savings of several percents. In addition, this scenario would increase the total service level. However, the environmental impact would be increased due to long cross-border road transport distances and longer land and sea transports from the warehouse. In addition, it was not possible to fully investigate whether such a distribution would be possible from a regulatory point of view.  A centralization in each country would have minor regulatory issues, it would lead to the smallest environmental impact and have a slight increase in service levels as well as a reduction for the total cost of one percent.

    The evaluation of the model showed that it produces reasonable results with the regulatory elements being the hardest to evaluate for the different scenarios. Regarding the detail level, the veterinary element could be accounted for by the warehousing element and the sea freight element split into transport from warehouse to domestic port and sea freight from domestic port to the destination port. The box-model, containing twelve elements, can be seen as generalizable for evaluating distribution structures in similar contexts, Overseas export of frozen food. However, the calculation performed within the model do probably only apply to the specific scenarios in the study.

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  • 13.
    Ahlstrom, Christer
    et al.
    Swedish Natl Rd and Transport Res Inst VTI, Linkoping, Sweden.
    Anund, Anna
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Prevention, Rehabilitation and Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Swedish Natl Rd and Transport Res Inst VTI, Linkoping, Sweden.
    Fors, Carina
    Swedish Natl Rd and Transport Res Inst VTI, Linkoping, Sweden.
    Akerstedt, Torbjorn
    Stockholm Univ, Sweden; Karolinska Inst, Sweden.
    The effect of daylight versus darkness on driver sleepiness: a driving simulator study2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 3, article id e12642Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 +/- 1.7years old) participated in a driving simulator experiment where they drove on a rural road. A 2x2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.

  • 14.
    Ahlström, Christer
    et al.
    Swedish National Rd and Transport Research Institute VTI, S-58195 Linkoping, Sweden.
    Kircher, Katja
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. Swedish National Rd and Transport Research Institute VTI, S-58195 Linkoping, Sweden.
    A Generalized Method to Extract Visual Time-Sharing Sequences From Naturalistic Driving Data2017In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 18, no 11, p. 2929-2938Article in journal (Refereed)
    Abstract [en]

    Indicators based on visual time-sharing have been used to investigate drivers visual behaviour during additional task execution. However, visual time-sharing analyses have been restricted to additional tasks with well-defined temporal start and end points and a dedicated visual target area. We introduce a method to automatically extract visual time-sharing sequences directly from eye tracking data. This facilitates investigations of systems, providing continuous information without well-defined start and end points. Furthermore, it becomes possible to investigate time-sharing behavior with other types of glance targets such as the mirrors. Time-sharing sequences are here extracted based on between-glance durations. If glances to a particular target are separated by less than a time-based threshold value, we assume that they belong to the same information intake event. Our results indicate that a 4-s threshold is appropriate. Examples derived from 12 drivers (about 100 hours of eye tracking data), collected in an on-road investigation of an in-vehicle information system, are provided to illustrate sequence-based analyses. This includes the possibility to investigate human-machine interface designs based on the number of glances in the extracted sequences, and to increase the legibility of transition matrices by deriving them from time-sharing sequences instead of single glances. More object-oriented glance behavior analyses, based on additional sensor and information fusion, are identified as the next future step. This would enable automated extraction of time-sharing sequences not only for targets fixed in the vehicles coordinate system, but also for environmental and traffic targets that move independently of the drivers vehicle.

  • 15.
    Ahlström, Christer
    et al.
    Swedish National Rd and Transport Research Institute VTI, S-58195 Linkoping, Sweden.
    Kircher, Katja
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. Swedish National Rd and Transport Research Institute VTI, S-58195 Linkoping, Sweden.
    Changes in glance behaviour when using a visual eco-driving system - A field study2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 58, p. 414-423Article in journal (Refereed)
    Abstract [en]

    While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate the visual behaviour of drivers interacting with such a system, implemented on a five-inch screen mounted above the middle console. Ten drivers participated in a real world, on-road driving study where they drove a route nine times (2 pre-baseline drives, 5 treatment drives, 2 post-baseline drives). The route was 96 km long and consisted of rural roads, urban roads and a dual-lane motorway. The results show that drivers look at the system for 5-8% of the time, depending on road type, with a glance duration of about 0.6 s, and with 0.05% long glances (amp;gt;2s) per kilometre. These figures are comparable to what was found for glances to the speedometer in this study. Glance behaviour away from the windscreen is slightly increased in treatment as compared to pre- and post-baseline, mirror glances decreased in treatment and post-baseline compared to pre-baseline, and speedometer glances increased compared to pre-baseline. The eco-driving support system provided continuous information interspersed with additional advice pop-ups (announced by a beep) and feedback pop-ups (no auditory cue). About 20% of sound initiated advice pop-ups were disregarded, and the remaining cases were usually looked at within the first two seconds. About 40% of the feedback pop-ups were disregarded. The amount of glances to the system immediately before the onset of a pop-up was clearly higher for feedback than for advice. All in all, the eco-driving support system under investigation is not likely to have a strong negative impact on glance behaviour. However, there is room for improvements. We recommend that eco-driving information is integrated with the speedometer, that optional activation of sound alerts for intermittent information is made available, and that the pop-up duration should be extended to facilitate self-regulation of information intake. (C) 2016 Elsevier Ltd. All rights reserved.

  • 16.
    Ahlström, Mattias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Development of an Attractive Network for Regional Bus Traffic in Dalarna County2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Även om direktbusstrafiken i Dalarnas län redan i dagsläget trafikerar relativt raka och snabba linjesträckningar anser länstrafikbolaget Dalatrafik att det finns potential till att ytterligare sänka restiderna för att locka fler resenärer. Fyra av länets viktigaste direktbusslinjer har därför studerats och för var och en av dessa har ett antal förändringsåtgärder tagits fram. Målet med förändringsåtgärderna har varit att, i första hand, åstadkomma en rakare linjesträckning och utreda hur mycket restiden skulle komma att förändras om bussen istället kör den nya vägen. Utifrån befintlig resandestatistik över hur många resenärer som reser på varje sträcka har den totala tidsbesparingen för samtliga förändringsåtgärder per linje beräknats och detta har givits ett monetärt värde. Genom täckningsanalyser har befolkningen inom upptagningsområdet kring varje hållplats beräknats, detta för att visa hur tillgängligheten till respektive linje förändras efter ett eventuellt införande av de föreslagna åtgärderna.

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  • 17. Order onlineBuy this publication >>
    Ait Ali, Abderrahman
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Methods for Capacity Allocation in Deregulated Railway Markets2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Faced with increasing challenges, railways around Europe have recently undergone major reforms aiming to improve the efficiency and competitiveness of the railway sector. New market structures such as vertical separation, deregulation and open access can allow for reduced public expenditures, increased market competition, and more efficient railway systems.

    However, these structures have introduced new challenges for managing infrastructure and operations. Railway capacity allocation, previously internally performed within monopolistic national companies, are now conferred to an infrastructure manager. The manager is responsible for transparent and efficient allocation of available capacity to the different (often competing) licensed railway undertakings.

    This thesis aims at developing a number of methods that can help allocate capacity in a deregulated (vertically separated) railway market. It focuses on efficiency in terms of social welfare, and transparency in terms of clarity and fairness. The work is concerned with successive allocation of capacity for publicly controlled and commercial traffic within a segmented railway market.

    The contributions include cost benefit analysis methods that allow public transport authorities to assess the social welfare of their traffic, and create efficient schedules. The thesis also describes a market-based transparent capacity allocation where infrastructure managers price commercial train paths to solve capacity conflicts with publicly controlled traffic. Additionally, solution methods are developed to help estimate passenger demand, which is a necessary input both for resolving conflicts, and for creating efficient timetables.

    Future capacity allocation in deregulated markets may include solution methods from this thesis. However, further experimentations are still required to address concerns such as data, legislation and acceptability. Moreover, future works can include prototyping and pilot projects on the proposed solutions, and investigating legal and digitalisation strategies to facilitate the implementation of such solutions.

    List of papers
    1. European Railway Deregulation: An overview of market organization and capacity allocation
    Open this publication in new window or tab >>European Railway Deregulation: An overview of market organization and capacity allocation
    2022 (English)In: Transportmetrica A: Transport Science, ISSN 2324-9935, E-ISSN 2324-9943, Vol. 18, no 3, p. 594-618Article in journal (Refereed) Published
    Abstract [en]

    Railway markets in Europe have been reorganized to allow competition between different operators. Thus, European railways have been vertically separated, separating infrastructure management from provisions of train services. This allows several train operators to compete for passengers and freight services. Different ways have emerged for vertical separation, capacity allocation and track access charges. This paper reviews, compares and discusses important deregulation aspects, using examples from a number of European countries to show different possible solutions. The study describes how competition has been introduced and regulated, with a particular focus on describing the different ways capacity is allocated and how conflicting requests by different train operators are resolved. It also reviews the related issue of how access charges are constructed and applied. Although guided by the same European legislation, we conclude that the studied railways have different deregulation outcomes, e.g., market organization, capacity allocation. Besides, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators. Although allowed by the legislation, market-based allocation is absent or never used. In order to foster more competition which can yield substantial social benefits, the survey indicates that most European railways still need to develop and experiment with more efficient and transparent capacity allocation procedures.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2022
    Keywords
    Railway deregulation, Vertical separation, Competition, Capacity allocation, Access charges
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-173445 (URN)10.1080/23249935.2021.1885521 (DOI)000621709500001 ()
    Note

    Funding: This research is part of the project Socio-economically efficient allocation of railway capacity, SamEff (Samhallsekonomiskt effektiv tilldelning av kapacitet pa jarnvagar) which is funded by a grant from the Swedish Transport Administration (Trafikverket). The authors are grateful to Jan-Eric Nilsson and Yves Crozet for reference recommendations as well as Russell Pittman, Steven Harrod, Roger Pyddoke and several anonymous reviewers for the valuable discussions and comments.

    Available from: 2021-02-19 Created: 2021-02-19 Last updated: 2022-10-17
    2. Pricing commercial train path requests based on societal costs
    Open this publication in new window or tab >>Pricing commercial train path requests based on societal costs
    2020 (English)In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 132, p. 452-464Article in journal (Refereed) Published
    Abstract [en]

    On deregulated railway markets, efficient capacity allocation is important. We study the case where commercial trains and publicly controlled traffic (“commuter trains”) use the same railway infrastructure and hence compete for capacity. We develop a method that can be used by an infrastructure manager trying to allocate capacity in a socially efficient way. The method calculates the loss of societal benefits incurred by changing the commuter train timetable to accommodate a commercial train path request, and based on this calculates a reservation price for the train path request. If the commercial operator’s willingness-to-pay for the train path exceeds the loss of societal benefits, its request is approved. The calculation of these benefits takes into account changes in commuter train passengers’ travel times, waiting times, transfers and crowding, and changes in operating costs for the commuter train operator(s). The method is implemented in a microscopic simulation program, which makes it possible to test the robustness and feasibility of timetable alternatives. We show that the method is possible to apply in practice by demonstrating it in a case study from Stockholm, illustrating the magnitudes of the resulting commercial train path prices. We conclude that marginal societal costs of railway capacity in Stockholm are considerably higher than the current track access charges.

    Place, publisher, year, edition, pages
    Elsevier, 2020
    Keywords
    Train timetables, Train conflicts, Capacity pricing, Railway capacity, Capacity allocation
    National Category
    Economics
    Identifiers
    urn:nbn:se:liu:diva-162784 (URN)10.1016/j.tra.2019.12.005 (DOI)000514014700030 ()2-s2.0-85076736383 (Scopus ID)
    Projects
    SamEff
    Note

    Funding agencies:  Swedish Transport Administration (Trafikverket) [Samhallsekonomiskt effektiv tilldelning av kapacitet pa jarnvagar]

    The accepted version is also available on the author's home page: 

    http://abdeaitali.github.io/

    Available from: 2019-12-18 Created: 2019-12-18 Last updated: 2021-12-01Bibliographically approved
    3. Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?
    Open this publication in new window or tab >>Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?
    2022 (English)In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 116, p. 188-198Article in journal (Refereed) Published
    Abstract [en]

    Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.

    Place, publisher, year, edition, pages
    Elsevier, 2022
    Keywords
    Waiting time, Crowding, Cost-benefit analysis, Implicit preference, Commuter train
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-181610 (URN)10.1016/j.tranpol.2021.11.025 (DOI)000751667100001 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    Funding: Swedish Transport Administration (Trafikverket) [samhadllsekonomiskt effektiv tilldelning av kapacitet pa jadrnvadgar]

    Available from: 2021-12-03 Created: 2021-12-03 Last updated: 2023-01-10Bibliographically approved
    4. A disaggregate bundle method for train timetabling problems
    Open this publication in new window or tab >>A disaggregate bundle method for train timetabling problems
    Show others...
    2020 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 16, article id 100200Article in journal (Refereed) Published
    Abstract [en]

    The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.

    Keywords
    Train timetabling, Disaggregation, Bundle methods, Lagrangian relaxation, Mathematical programming
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-165781 (URN)10.1016/j.jrtpm.2020.100200 (DOI)000597313000002 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    The accepted version is also available on the author's home page: 

    http://abdeaitali.github.io/

    Funding agencies: Swedish Transport Administration (Trafikverket)

    Available from: 2020-05-24 Created: 2020-05-24 Last updated: 2021-12-01
    5. The value of additional data for public transport origin–destination matrix estimation
    Open this publication in new window or tab >>The value of additional data for public transport origin–destination matrix estimation
    2022 (English)In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 14, no 2, p. 419-439Article in journal (Refereed) Published
    Abstract [en]

    Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.

    Place, publisher, year, edition, pages
    Springer, 2022
    Keywords
    Dynamic origin-destination; OD estimation; entropy maximization; lagrangian relaxation; smart card; public transport
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-179343 (URN)10.1007/s12469-021-00282-0 (DOI)000695756100001 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    Funding: Swedish National Road and Transport Research Institute (VTI); Swedish Transport Administration (Trafikverket)

    Available from: 2021-09-19 Created: 2021-09-19 Last updated: 2022-10-14
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  • 18.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI Swedish National Road and Transport Research Institute, Transport Economics, Stockholm.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    European Railway Deregulation: An overview of market organization and capacity allocation2022In: Transportmetrica A: Transport Science, ISSN 2324-9935, E-ISSN 2324-9943, Vol. 18, no 3, p. 594-618Article in journal (Refereed)
    Abstract [en]

    Railway markets in Europe have been reorganized to allow competition between different operators. Thus, European railways have been vertically separated, separating infrastructure management from provisions of train services. This allows several train operators to compete for passengers and freight services. Different ways have emerged for vertical separation, capacity allocation and track access charges. This paper reviews, compares and discusses important deregulation aspects, using examples from a number of European countries to show different possible solutions. The study describes how competition has been introduced and regulated, with a particular focus on describing the different ways capacity is allocated and how conflicting requests by different train operators are resolved. It also reviews the related issue of how access charges are constructed and applied. Although guided by the same European legislation, we conclude that the studied railways have different deregulation outcomes, e.g., market organization, capacity allocation. Besides, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators. Although allowed by the legislation, market-based allocation is absent or never used. In order to foster more competition which can yield substantial social benefits, the survey indicates that most European railways still need to develop and experiment with more efficient and transparent capacity allocation procedures.

    Download full text (pdf)
    fulltext
  • 19.
    Ait Ali, Abderrahman
    et al.
    The Swedish National Road and Transport Research Institute (VTI), Stockholm, Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The value of additional data for public transport origin–destination matrix estimation2022In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 14, no 2, p. 419-439Article in journal (Refereed)
    Abstract [en]

    Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.

    Download full text (pdf)
    fulltext
  • 20.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Stockholm.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Transport Administration (Trafikverket), Solna.
    Warg, Jennifer
    Royal Institute of Technology (KTH), Stockholm.
    Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?2022In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 116, p. 188-198Article in journal (Refereed)
    Abstract [en]

    Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.

    Download full text (pdf)
    fulltext
  • 21.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Trafikverket.
    Warg, Jennifer
    KTH.
    Measuring the Socio-economic Benefits of Train Timetables: Application to Commuter Train Services in Stockholm2017In: / [ed] Domokos Esztergár-Kiss, Tamás Mátrai, János Tóth, István Varga, 2017, Vol. 27, p. 849-856Conference paper (Refereed)
    Abstract [en]

    On highly used railway lines with heterogeneous traffic, timetabling is challenging. In particular, the limited existing capacity means that to guarantee an acceptable level of quality, the infrastructure manager must cancel some train services on the expense of others. In this article, we study the conflict between commercial long-distance trains and subsidized commuter trains with a socio-economic perspective (i.e. travelers and train operators). The study attempts to answer the following question: What is the socio-economic effect of modifying the timetable of a commuter service?

    The case study treats the commuter train services in Stockholm. Trip data was collected from the local commuter train operator. An entropy maximization-based model was implemented to estimate the dynamic network Origin-Destination (OD) matrix. This dynamic matrix, of one full working day, was then used to estimate the number of travelers per train, and further converted for use in the microscopic simulation tool RailSys. Travel and waiting time are estimated for each OD pair and with that the generalized costs for the travelers and operators. The effect of crowding in the trains is included in the estimation. The article can be considered as an initiation to a novel method to calculate effects of changes in commuter train timetables. This novel approach enables to price commercial train slots in the capacity allocation process such as in an auction. It provides a new way to estimate the local train operator´s valuation of the different parameters (i.e. waiting, travel time and interchanges). Using RailSys for the estimation of times makes it possible to include capacity aspects that normally are difficult to reveal.

  • 22.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Natl Rd & Transport Res Inst VTI, Sweden.
    Lidén, Tomas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Natl Rd & Transport Res Inst VTI, Sweden.
    Minimal utilization rate for railway maintenance windows: a cost-benefit approach2022In: European Journal of Transport and Infrastructure Research, ISSN 1567-7133, E-ISSN 1567-7141, Vol. 22, no 2, p. 108-131Article in journal (Refereed)
    Abstract [en]

    Methods for economic assessment are often used in the rail sector to evaluate large infrastructure investments such as new high-speed lines. With larger networks and ageing infrastructure, these methods can also be used for planning maintenance. In this paper, we focus on the newly introduced concept of maintenance windows in Sweden. These are pre-allocated slots in the train timetable dedicated to performing, among others, periodic/frequent maintenance activities. To justify the pre-allocation of such windows, this study presents a method to find minimal utilization rates depending on window designs and traffic situations. Using a cost-benefit approach, the windows are assessed using a total social cost including work costs, loss in traffic production and reliability gains in future traffic. Based on a case study from the Southern main line in Sweden, we study the minimal utilization rate in different test scenarios, i.e., night or day shifts, asset degradation functions and designs of maintenance windows. The results show that lower utilization rates (4-42%) can be accepted during low-volume traffic or for partial closures, while higher utilization rates (47-83%) are required for full closures during high-volume traffic. Whether the rates are measured as the share of used window time or the share of utilized windows is less important, especially when higher utilization is required. Sensitivity analyses of asset knowledge indicate that parameters such as asset degradation function and minimum asset quality (and to a lesser extent traffic volume, discount rate and failure likelihood) can have a substantial effect on the minimum required utilization rates.

  • 23.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Sweden.
    Lindberg, Per Olov
    Swedish National Road and Transport Research Institute (VTI), Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Nilsson, Jan-Eric
    Swedish National Road and Transport Research Institute (VTI), Sweden.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A disaggregate bundle method for train timetabling problems2020In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 16, article id 100200Article in journal (Refereed)
    Abstract [en]

    The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.

    Download full text (pdf)
    fulltext
  • 24.
    Akililu, Meaza Negash
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Verification of Rural Traffic Simulator, RuTSim 22012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traffic models based on micro-simulation are becoming increasingly important as traffic analysistools. Due to the detailed traffic description, different micro-simulation models are needed tosimulate different traffic environments. The Rural Traffic Simulator, RuTSim, is a unique microtrafficsimulation model for traffic on rural roads. RuTSim is developed at VTI with support fromthe Swedish Transport Administration. Currently, a new version of the RuTSim model has beenimplemented based on the earlier one but with some enhancements. Due to these enhancements,the new implementation of RuTSim should be verified before being used to analyze real worldproblems.

    In this master’s thesis, a verification of the new implementation of the RuTSim model, RuTSim 2,has been carried out. This paper includes a description of traffic micro-simulation models forrural roads in general and a description of RuTSim model in particular. Common verificationtechniques of the simulation models are also discussed in this study.

    Based on the theoretical assessments, a model-to-model comparison verification scheme isselected to verify the RuTSim 2 model. That is, the model verification is performed by comparingthe simulation outputs from RuTSim 2 to the old version of RuTSim (RuTSim 1), since RuTSim1 is well verified and calibrated. Statistical hypothesis tests are used to check whether the meanand standard deviation differences of the simulation outputs between the two simulators aresignificant or not.

    Based on the verification results, the new version of the RuTSim model has comparable modelingof vehicle-vehicle and vehicle-infrastructure interactions as the old version. Furthermore, thehypothesis test results show that the differences of the mean simulation results of the twosimulators are not significant. Therefore, the new implementation of RuTSim model, RuTSim 2,has been proven to be equivalent model as the old version.

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  • 25.
    Al Haji, Ghazwan
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Smart traffic calming measures for smart cities: a pre-study2018Report (Other academic)
    Abstract [en]

    Traffic calming measures, such as speed bumps and elevated crossing points, are used to reduce speed, to prevent overtaking and generally contribute to a safer traffic situation. However, they might also cause increased response times for rescue vehicles (e.g. ambulances or fire trucks). An alternative to the conventional traffic calming measures is so-called smart traffic calming measures. These can determine when a vehicle approaches, whose journey should not be hindered, and adjust to allow for free passage for this vehicle.

    This report gives an overview of the problem, and some examples of smart  traffic calming measures are discussed. Special focus is put on the wireless communication necessary to detect emergency vehicles. Furthermore, existing challenges and possible solutions for traffic calming measures and the communication needed to make them smart are discussed.

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    Smart traffic calming measures for smart cities - a pre-study
  • 26.
    Al-ani, Neeran
    et al.
    Linköping University, Department of Science and Technology.
    Boutros, Mireille
    Linköping University, Department of Science and Technology.
    Flerpatientbesök – ett förbättringsförslag baserat på en analys av den dagligaverksamheten vid vårdcentralen Cityhälsan Söder: En kartläggning på Blodtrycksmottagning och Astma/KOL- mottagning med hjälp av Lean2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Östergötland County Council has begun to implement “Lean-Thinking" in healthcare service. Staff at healthcare service has experienced new challenges. Health care quality cannot anymore be measured only by medical treatment results, other factors are of importance, for example accessibility.

    The management of the health centre “Cityhälsan Söder” wished to identify problems that affect patient flow and requested proposals for improvements which could increase the number of patients cared for at Blood Pressure-department and Asthma/COL- department.

    For the mapping of the activities performed by a nurse during a working day, two data collection methods were used: observation and survey. Collected data were analysed in relation to the frame of reference concerning theories of Lean healthcare and logistics. Focus in the identification of problems was to improve the utilization of nursing time to allow more patient visits. 

    In the analysis eight types of wastes are especially used: overproduction, waiting, transportation, extra-processing, inventory, motion, defects and non-utilised skills. From the healthcare logistics point of view, the cancelations problem, lack of resources and matching capacity with demand was also analysed.

    To increase staff knowledge of how service may work better it was suggested to take advantage of the staff's creativity by expanding the personnel’s perception of patient flow in order to match capacity with demand. Other proposals concerned waiting-list management, which aims to introduce direct time booking of upcoming patient visits at both departments, freeing administrative time that can be spent to accommodate more patients. To standardize medical examinations on Asthma/COL-departments is also a proposal.

    IT-solutions for both departments may also create opportunities for more patient visits. A film that prepares the patient by teaching the correct blowing technique for the visit on Asthma/COL-department may accelerate medical examinations and free time that can be used better.

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  • 27.
    Al-Dabbas, Khaled
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Analysis of GHG emissions reduction from road transport: a case study of the German passenger vehicles2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transportation and energy play an essential role in modern society. Since the Industrial Revolution, fossil fuels have enabled great advancements in human society. Within this process, Internal Combustion Engines Vehicles (ICEVs) played a significant role in guaranteeing reliable and affordable long-distance transportation. However, the subsequent increase of the Motorized Private Transport resulted in undesired effects such as pollution. One instrument in reducing the Greenhouse Gas (GHG) emissions of the transport sector is to shift from the conventional ICEVs toward zero local emission vehicles. Electric Vehicles (EVs) are being promoted worldwide as a suitable powertrain technology that could replace the ICEVs. However, unless combined with electricity from renewable generation technologies the EVs will not effectively reduce GHG emissions. Through the simulation of future transport and energy sector scenarios in Germany, the GHG emission reductions have been analyzed. Techno-economic and environmental characteristics for several powertrain technologies under several vehicles charging strategies are evaluated. The thesis explores the impact of charging EVs on the electrical grid. The result show that EVs using smart charging strategies that support Vehicle-to-grid (V2G) are capable of fulfilling mobility needs of users while providing substantial flexibility to the electrical grid. Such flexibility can facilitate the future expansion of non-dispatchable Renewable Energy Sources (RES).

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    Analysis of GHG emissions reduction from road transport: a case study of the German passenger vehicles
  • 28.
    Aldin, Niklas
    Linköping University, Department of Management and Engineering, Logistics Management. Linköping University, The Institute of Technology.
    The Luna Case within Bergman & Beving Tools: Changes in Logistics Management2002Report (Other academic)
    Abstract [en]

    Companies conducting business in multiple marketing channels need logistics and IT solutions that support their wide array of strategy and operations. Those, and other firms, do not solely rely on new concepts but also on continuously developing their businesses in the interaction between marketing and logistics. This case study will show on these aspects - how marketing and logistics may be integrated in such a channel environment by continuously developing the business as well as through new approaches in information technology - electronic commerce.

    The Luna case Within Bergman & Beving Tools illustrates the development of a medium sized distributor from catalogue based firm to flow co-ordinator in a group constellation, a change from a single steady going to a multiple requirement demanding marketing channel. Luna is a transaction intensive distributor of tools and machinery equipment with long experience in logistics and information technology. The company is guarantor for assortment quality, fast and reliable logistics through sophisticated IT solutions as well as value added competence in its trade relations with dealers and end customers. Independent dealers and end customers are found in Nordic industrial, construction, engineering, administration and consumer sectors. Bergman & Beving Tools is parent company to seven distributors of which Luna is the largest.

    To start with, this case describes the background development of the business in the fields of marketing, logistics and information technology until 1993. The second part between 1993 and 2001 describes how the marketing agenda has changed, how electronic commerce has been used to develop the business and changes in logistics, both on operational and strategic levels. As a whole the case describes changes in logistics management and how that has interacted with market development.

  • 29.
    Aldén, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Odebo, Stina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The use of ground equipment at airports2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    För att flygplatser ska kunna ha så hög kapacitet som möjligt krävs effektivisering av alla delar av flygplatsverksamheten. Denna studie har identifierat problem och utvecklingsområden av användningen av markutrustning på flygplatser. I studien har det även analyserats effektiviseringsmöjligheter. Några exempel på problem och utvecklingsområden som funnits är att utrustningen är utspridd på flygplatsen och att det finns för mycket utrustning. Ett av lösningsförslagen som föreslås i rapporten är att en tredjepartsaktör äger all markutrustning på flygplatsen och sedan bedriver uthyrning av utrustningen till användarna.

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  • 30.
    Alfredsson, Nina
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Angvarson, Josefin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    An analysis of the robustness of SAS crew schedules2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Scandinavian Airlines (SAS) är nordens största flygbolag och har en besättning på 5 000 personer med baser i Danmark, Norge och Sverige. SAS besättningsscheman för kabinpersonal med bas Stockholm samt piloter med samma bas och kvalifikationer för flygplanstypen Boeing 737 har analyserats. Genomförda förändringar efter att scheman publicerats under 2013 och 2014 har kartlagts. Förändringarna har utretts för att fastställa hur stor andel av ett schema som genomförs som planerat. Vidare har ett mätetal som även tar hänsyn till antalet ändringar som sker från planerad ledighet och sjukdom till någon form av produktion tagits fram, mätetalet kallas förändringskvot. Andelen avvecklat enligt plan och förändringskvoten är beräknade per produktionsdag. Mätetalens resultat är relativt jämna för 2013 och 2014. År 2013 avvecklades i genomsnitt 75 % av panerade produktionsdagar och förändringskvoten utgjorde i genomsnitt 30 %. Motsvarande siffror för år 2014 var 77 % och 29 %.

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  • 31.
    Algers, Staffan
    et al.
    KTH, Transport och lokaliseringsanalys (stängd 20110301).
    Eliasson, Jonas
    Transek AB, Solna, Sweden.
    Mattsson, Lars-Göran
    KTH, Transport och lokaliseringsanalys (stängd 20110301).
    Is it time to use activity-based urban transport models? A discussion of planning needs and modelling possibilities2005In: The annals of regional science, ISSN 0570-1864, E-ISSN 1432-0592, Vol. 39, no 4, p. 767-789Article in journal (Refereed)
    Abstract [en]

    For some decades now, transport researchers have put considerable efforts into developing what is called activity-based approaches for modelling urban travel demand. The basic idea is that travel demand is derived from people's desires to take part in different activities. In particular, the interrelationships among different activities with respect to temporal and spatial constraints are in focus. It means that such models treat the activities and the travelling of the households with respect to where and when the activities can be carried out and how they may be scheduled, given characteristics of the households and potential opportunities, the transport networks and various institutional constraints. We discuss what demands we see on future travel demand models, with a focus on urban analysis. This discussion is somewhat biased towards what role activity-based models could play in meeting these demands. We then review in some detail three prominent and distinctly different representatives of operational activity-based models to give an indication of what new modelling possibilities they offer. Theoretical appeal, empirical validity, usefulness for planning, need for data and easiness of implementation are discussed. In the final section we draw some conclusions about the prospects of these models and of their descendants.

  • 32.
    Ali, Zakariya
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Qya, Josef
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Impact of production strategies on inventory management - A case study at a Paper Mill2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Kundundersökningar har visat att det undersökta pappersbruket bör förbättra sina leveransledtider. En lösning för detta anses vara en förändring av nuvarande produktionsstrategi. Den nuvarande produktionsstrategin är kundorderproduktion och de alternativa strategierna som kommer att undersökas under studien är lagerorderproduktion och hybridsystem. Syftet med studien är att undersöka, jämföra och analysera olika produktionsstrategier (lagerorderproduktion, kundorderproduktion och hybridsystem) samt att utvärdera deras inverkan på lagerstyrningen. För att uppnå syftet har studien baserats på tre frågeställningar: Vilka för- och nackdelar har produktionsstrategierna på färdigvarulagret samt vilka nyckeltal behöver identifieras? Vilka problem gällande produktion- och lagerstyrning stöter en produktionsplanerare i ett pappersbruk på? Vilken påverkan har produktionsstrategierna på färdigvarulagret hos det undersökta pappersbruket utifrån identifierade nyckeltal.

    Frågeställningarna besvarades genom att utföra en litteraturstudie om olika produktionsstrategier och lagerstyrning. Med hjälp av litteraturstudien har lämpliga nyckeltal identifierats för att analysera inverkan på lagerstyrning. Utöver litteraturstudien har intervjuer utförts för att skapa en bredare förståelse kring hur det undersökta pappersbruket i helhet ser på produktionsstrategier och dess inverkan på lagerstyrning. Slutligen utfördes en deskriptiv analys för att beräkna de identifierade nyckeltalen.

    Resultatet från första frågeställningen visade att olika produktionsstrategier kan bidra med olika för- och nackdelar. Dessutom anses en fördel vara en bidragande faktor till en nackdel, exempelvis för hybridsystem kan en förbättring av leveranstider medföra till problem med lagerfyllning. Det är viktigt att även ta hänsyn till hur marknaden ser ut och vilka faktorer som kan påverka samt vad kunderna efterfrågar. Resultatet från andra frågeställningen presenterade tre sammanfattande problem från de utförda intervjuerna om nuvarande produktionsstrategi och lagerstyrning. När det gäller valet av produktionsstrategi ansåg majoriteten av intervjupersonerna att produktionsstrategin hybridsystem har bäst inverkan på lagerstyrningen endast om ett antal villkor uppfylls. Villkoren är att företaget arbetar med stora volymer, har många kunder och erhåller en hög efterfrågan på standardprodukter. För frågeställning tre visade sig att produkt A hade lägst lagerföringskostnad medan produkt C hade högst lagerföringskostnad. För nyckeltalet genomloppstid visade sig att produkt C tog kortast tid och produkt B istället tog längst tid. När det gäller lägsta lagernivå finns det inga bestämda lagernivåer eller beställningspunkt som det undersökta pappersbruket förhåller sig till under produktion mot kundorder. Det resulterar till att den lägsta lagernivån är lika med noll. Om företaget producerar mot lagerorder kommer lägsta lagernivå vara 14 800 ton/år för produkt A, 20 891 ton/år för produkt B och 23 161 ton/år för produkt C. Däremot för ett hybridsystem måste företaget ta hänsyn till genomloppstiden eftersom det påverkar valet av lägsta lagernivå. Produkter med en längre genomloppstid erhåller en lägsta lagernivå nära till den förväntade producerade volymen. Produkter med kortare genomloppstid kan därmed produceras utan att begränsa produktion av resterande produkter därför kan de lagras i lägre volymer.

    Slutsatsen av studien är att företaget bör ändra produktionsstrategi till ett hybridssystem med hänsyn till det presenetrade resultatet och en ständig analys av marknaden. 

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  • 33. Order onlineBuy this publication >>
    Allström, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Highway Traffic State Estimation and Short-term Prediction2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Traffic congestion is increasing in almost all large cities, leading to a number of negative effects such as pollution and delays. However, building new roads is not a feasible solution. Instead, the use of the existing road network has to be optimized, together with a shift towards more sustainable transport modes. In order to achieve this there are several challenges that needs to be addressed. One challenge is the ability to provide accurate information about the current and future traffic state. This information is an essential input to the traffic management center and can be used to influence the choices made by the travelers. Accurate information about the traffic state on highways, where the potential to manage and control the traffic in general is very high, would be of great significance for the traffic managers. It would help the traffic managers to take action before the system reaches congestion and limit the effects of it. At the same time, the collection of traffic data is slowly shifting from fixed sensors to more probe based data collection. This requires an adaptation and further development of the traditional traffic models in order for them to handle and take advantage of the characteristics of all types of data, not just data from the traditionally used fixed sensors.

    The objective of this thesis is to contribute to the development and implementation of a model for estimation and prediction of the current and future traffic state and to facilitate an adaptation of the model to the conditions of the highway in Stockholm. The model used is a version of the Cell Transmission Model (CTM-v) where the velocity is used as the state variable. Thus, together with an Ensemble Kalman Filter (EnKF) it can be used to fuse different types of point speed measurements. The model is developed to run in real-time for a large network. Furthermore, a two-stage process used to calibrate the model is implemented. The results from the calibration and validation show that once the model is calibrated, the estimated travel times corresponds well with the ground truth travel times collected from Bluetooth sensors.

    In order to produce accurate short-term predictions for various networks and conditions it is vital to combine different methods. We have implemented and evaluated a hybrid prediction approach that assimilates parametric and non-parametric short-term traffic state prediction. To predict mainline sensor data we use a neural network, while the CTM-v is ran forward in time in order to predict future traffic states. The results show that both the hybrid approach and the CTM-v prediction without the additional predicted mainline sensor data is superior to a naïve prediction method for longer prediction horizons.

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  • 34.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Archer, Jeffery
    Sweco Infrastructure, Sweden.
    Bayen, Alexandre
    University of California, Berkeley, USA.
    Blandin, Sebastian
    University of California, Berkeley, USA.
    Butler, Joe
    California Center for Innovative Transportation. USA.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Koutsopoulose, Haris N
    Royal Institute of Technology (KTH), Sweden.
    Lundgren, Jan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Rahmani, Mahmood
    Royal Institute of Technology (KTH), Sweden.
    Tossavainen, Olli-Pekka
    NAVTEQ LLC, USA.
    Mobile Millennium Stockholm2011In: 2nd International Conference on Models and Technologies for Intelligent Transportation Systems, 2011Conference paper (Other academic)
  • 35.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Barceló, Jaume
    Department of Statistics and Operations Research, Universitat Politècnica de Catalunya.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Grumert, Ellen
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Traffic management for smart cities2017In: Designing, developing, and facilitating smart cities: urban design to IoT solutions. Part III / [ed] Vangelis Angelakis, Elias Tragos, Henrich C. Pöhls, Adam Kapovits and Alessandro Bassi, Switzerland: Springer, 2017, p. 211-240Chapter in book (Other academic)
    Abstract [en]

    Smart cities, participatory sensing as well as location data available in communication systems and social networks generates a vast amount of heterogeneous mobility data that can be used for traffic management. This chapter gives an overview of the different data sources and their characteristics and describes a framework for utilizing the various sources efficiently in the context of traffic management. Furthermore, different types of traffic models and algorithms are related to both the different data sources as well as some key functionalities of active traffic management, for example short-term prediction and control.

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    Traffic management for smart cities
  • 36.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology. Sweco TransportSystem, Stockholm, Sweden.
    Bayen, Alexandre M.
    University of California Berkeley, USA.
    Fransson, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Sweco TransportSystem, Stockholm, Sweden.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Patire, Anthony D.
    University of California Berkeley, USA.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Sandin, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Calibration Framework based on Bluetooth Sensors for Traffic State Estimation Using a Velocity based Cell Transmission Model2014In: Transportation Research Procedia, ISSN 2352-1465, Vol. 3, p. 972-981Article in journal (Refereed)
    Abstract [en]

    The velocity based cell transmission model (CTM-v) is a discrete time dynamical model that mimics the evolution of the traffic velocity field on highways. In this paper the CTM-v model is used together with an ensemble Kalman filter (EnKF) for the purpose of velocity sensor data assimilation. We present a calibration framework for the CTM-v and EnKF. The framework consists of two separate phases. The first phase is the calibration of the parameters of the fundamental diagram and the second phase is the calibration of demand and filter parameters. Results from the calibrated model are presented for a highway stretch north of Stockholm, Sweden.

  • 37.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ringdahl, Rasmus
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Bayen, Alexandre M.
    Department of Civil and Environmental Engineering, University of California.
    Patire, Anthony D.
    Department of Civil and Environmental Engineering, University of California.
    A hybrid approach for short-term traffic state and travel time prediction on highways2016In: TRB 95th annual meeting compendium of papers, 2016Conference paper (Refereed)
    Abstract [en]

    Traffic management and traffic information are essential in urban areas, and require a good knowledge about both the current and the future traffic state. Both parametric and non-parametric traffic state prediction techniques have previously been developed, with different advantages and shortcomings. While non-parametric prediction has shown good results for predicting the traffic state during recurrent traffic conditions, parametric traffic state prediction can be used during non-recurring traffic conditions such as incidents and events. Hybrid approaches, combining the two prediction paradigms have previously been proposed by using non-parametric methods for predicting boundary conditions used in a parametric method. In this paper we instead combine parametric and non-parametric traffic state prediction techniques through assimilation in an Ensemble Kalman filter. As non-parametric prediction method a neural network method is adopted, and the parametric prediction is carried out using a cell transmission model with velocity as state. The results show that our hybrid approach can improve travel time prediction of journeys planned to commence 15 to 30 minutes into the future, using a prediction horizon of up to 50 minutes ahead in time to allow the journey to be completed.

  • 38.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ringdahl, Rasmus
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Bayen, Alexandre M.
    Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
    Patire, Anthony D.
    Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
    Hybrid Approach for Short-Term Traffic State and Travel Time Prediction on Highways2016In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, Vol. 2554, p. 60-68Article in journal (Refereed)
    Abstract [en]

    Traffic management and traffic information are essential in urban areas and require reliable knowledge about the current and future traffic state. Parametric and nonparametric traffic state prediction techniques have previously been developed with different advantages and shortcomings. While nonparametric prediction has shown good results for predicting the traffic state during recurrent traffic conditions, parametric traffic state prediction can be used during nonrecurring traffic conditions, such as incidents and events. Hybrid approaches have previously been proposed; these approaches combine the two prediction paradigms by using nonparametric methods for predicting boundary conditions used in a parametric method. In this paper, parametric and nonparametric traffic state prediction techniques are instead combined through assimilation in an ensemble Kalman filter. For nonparametric prediction, a neural network method is adopted; the parametric prediction is carried out with a cell transmission model with velocity as state. The results show that the hybrid approach can improve travel time prediction of journeys planned to commence 15 to 30 min into the future, with a prediction horizon of up to 50 min ahead in time to allow the journey to be completed

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  • 39.
    Allström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Evaluation of travel time estimation based on LWR-v and CTM-v: A case study in Stockholm2012In: 15th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2012, Piscataway, N.J, USA: IEEE , 2012, p. 1644-1649Conference paper (Refereed)
    Abstract [en]

    Real-time estimations of current and future traffic states are an essential part of traffic management and traffic information systems. Within the Mobile Millennium project considerable effort has been invested in the research and development of a real-time estimation system that can fuse several sources of data collected in California. During the past year this system has been adapted to also handle traffic data collected in Stockholm. This paper provides an overview of the model used for highways and presents results from an initial evaluation of the system. As part of the evaluation process, GPS data collected in an earlier field-test and estimations generated by the existing system used by the TMC in Stockholm, are compared with the estimations generated by the Mobile Millennium system. Given that the Mobile Millennium Stockholm system has not undergone any calibration, the results from the evaluation are considered promising. The estimated travel times correspond well to those measured in the field test. Furthermore, the estimations generated by the Mobile Millennium system can be regarded as superior to those of existing traffic management system in Stockholm. The highway model was found to perform well even with a reduction in the number of sensors providing data. The findings of this study indicate the robustness of the Mobile Millennium system and demonstrate how the system can be migrated to other geographical areas with similar sources of available data.

  • 40.
    Alm, Johanna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Plantin Vantell, My
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Problems and potential improvements of the order- and delivery process at Region Östergötland2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Region Östergötland (RÖ) har många olika order- och leveransprocesser varav en kallas för den yttre order- och leveransprocessen. Denna process är det informations- och materialflöde där beställning går direkt till leverantör och inte via den centraldepå som finns. Det är många personer som är inblandade och som ansvarar för olika delar av den yttre order- och leveransprocessen, samtidigt som personerna i fråga även arbetar på olika avdelningar. Detta tillsammans med att delar av processen sköts av en extern aktör har lett till att ingen ansvarar för hela processen i sig, och således finns inte heller en sammanhållen bild över processen. Syftet med rapporten är att ge en sammanhållen bild av den yttre order- och leveransprocessen samt belysa eventuella problem och ge förslag på förändringar som kan förbättra processen.

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  • 41.
    Al-Nazary, Ashur
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Youssef, Randy
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The impact of climate change on aviation in Sweden2024Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
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  • 42.
    Al-Salehi, Ester
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Interventions to Reduce Car Use: A Meta-Analysis2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transportation has become an essential part of people's lives to move from one place to another, increasing the transport mobility for passengers. Therefore, road transport accounts for the second largest contributor to greenhouse gas emissions in Europe, and to increased congestion. Hence, reducing the share of car use can lead to reduced greenhouse gas emissions, congestion, etc. However, not all types of car travel could be reduced, therefore there is a need to maintain certain transport demand. Instead, passenger transport could be made more efficient, such as utilizing time, space, vehicles, and fuel in the movement without any waste. Efficiency in passenger transport could be achieved through a variety of interventions that aim to decrease the share of car use. The aim of this master thesis is to state interventions that reduce the share of car use and achieve efficient passenger transport.

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  • 43.
    Al-salehi, Ester
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Litorell, Erik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Follow-up of Delivery Reliability and Transportation Forecasts For Construction Projects2021Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Detta arbete studerar leveranspålitlighet samt prognosavvikelser kopplade till leveranser av byggmaterial som anländer till ett stort byggprojekt i Stockholm.

  • 44.
    Altkvist, Therese
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hultman, Hanna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Godsspårningssystem för landstinget i Östergötland2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Landstinget i Östergötland efterfrågar en högre spårbarhet för läkemedel och övrigt gods. Idag används godsspårningssystemet Arrival, levererat av Pitney Bowes för godsmottagningarna på Universitetssjukhuset i Linköping, Vrinnevisjukhuset i Norrköping samt på Lasarettet i Motala. För att kunna rekommendera vad Landstinget i Östergötland bör tänka på vid upphandling av ett eventuellt nytt godsspårningssystem har deras nuvarande system utvärderats och en omvärldsbevakning av alternativa spårningssystem har genomförts. Studien av Arrival baserades på fältstudier som genomfördes på godsmottagningar på Universitetssjukhuset i Linköping och Lasarettet i Motala samt genom intervjuer med användare och en kunnig brukare av systemet. Denna utvärdering av systemet resulterade i att ett antal förbättringsområden identifierades. I omvärldsbevakningen undersöktes tre alternativa godsspårningssystem från tre olika leverantörer. Ett nyutvecklat godsspårningssystem av ISS, TrueMobile Track and Trace av Optidev samt SendSuite av Pitney Bowes. Resultatet av detta examensarbete är ett antal rekommendationer till Landstinget i Östergötland avseende spårning av gods. Landstinget bör inkludera åsikter från systemanvändare vid upphandling samt erbjuda dem en fullgod utbildning i det initierande stadiet av en eventuell implementering av ett nytt godsspårningssystem. Landstinget bör vidare efterfråga funktioner som avläsningsverktyg som kan synkronisera trådlöst och en funktion för en mer tidseffektiv leverans av flera paket samt se över möjligheterna med RFID.

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  • 45.
    Anany, Hossam
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Effectiveness of a speed advisory traffic signal system for Conventional and Automated vehicles in a smart city2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project presents a traffic micro simulation study that investigates the state-of-the-art in traffic management "Green Light Optimal Speed Advisory (GLOSA)" for vehicles in a smart city. GLOSA utilizes infrastructure and vehicles communication through using current signal plan settings and updated vehicular information in order to influence the intersection approach speeds. The project involves simulations for a mixed traffic environment of conventional and automated vehicles both connected to the intersection control and guided by a speed advisory traffic management system. Among the project goals is to assess the effects on traffic performance when human drivers comply to the speed advice. The GLOSA management approach is also accessed for its potential to improve traffic efficiency in a full market penetration of connected automated vehicles with enhanced capabilities such as having shorter time head ways.

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    Effectiveness of a speed advisory traffic signal system for Conventional and Automated vehicles in a smart city
  • 46.
    Anany, Hossam
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Effectiveness of a Speed Advisory Traffic Signal System for Conventional and Automated vehicles in a Smart City2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project investigates the state-of-the-art in traffic management "Green Light Optimal Speed Advisory (GLOSA)" for vehicles in a smart city. GLOSA utilizes infrastructure and vehicles communication through using current signal plan settings and updated vehicular information in order to influence the intersection approach speeds.

    The project involves traffic microscopic simulations for a mixed traffic environment of conventional and automated vehicles (AVs) both connected to the intersection control and guided by a speed advisory traffic management system. Among the project goals is to assess the effects on traffic performance when human drivers comply to the speed advice. The GLOSA management approach is accessed for its potential to improve traffic efficiency in a full market penetration of connected AVs with absolute compliance. The project also aims to determine the possible outcome resulting from enhancing the AVs capabilities such as implementing short time headways between vehicles in the future. 

    The best traffic performance results achieved by operating GLOSA goes for connected AVs with the lowest simulated time headway (0.3 sec). The waiting time reduction reaches 95% and trip delay lessens to 88 %.

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  • 47. Order onlineBuy this publication >>
    Andersson, Angelica
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Mode choice modelling of long-distance passenger transport based on mobile phone network data2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Reliable forecasting models are needed to achieve the climate related goals in the face of increasing transport demand. Such models can predict the long-term behavioural response to policy interventions, including infrastructure investments, and thus provide valuable pre-dictions for decision makers. Contemporary forecasting models are mainly based on national travel surveys. Unfortunately, the response rates of such surveys have steadily declined, implying that the respondents become less representative of the whole population. A particular weakness is that it is likely that respondents with a high valuation of time are less willing to respond to surveys (because they have less time available for such), and therefore there is a high chance that they are underrepresented among the respondents. The valuation of time plays an important role for the cost benefit analyses of public policies including transport investments, and there is no reliable way of controlling for this uneven sampling of time preferences. Fortunately, there is simultaneously an increase in the number of signals sent between mobile phones and network antennae, and research has now reached the point where it is possible to determine not only the travel destination but also the travel mode based on mobile phone network antennae connections. The aim of this thesis is to investigate if and how mobile phone network data can be used to estimate transportation mode choice demand models that can be used for forecasting and planning. Key challenges with using this data source in the context of mode choice models are identified and met. The identified challenges include uncertainty in the choice variable, the difficulty to distinguish car and bus trips, and the lack of information about the trip purpose. In the first paper we propose three possible model formulations and analyse how the uncertainty in the choice outcome variable would play a role in the different model formulations. We also conclude that it is indeed possible to estimate mode choice demand models based on mobile phone network data, with good results in terms of behavioural interpretability and significance. In the second paper we estimate models using a nested logit structure to account for the difficulty in separating bus and car, and a latent class model specification to meet the challenge of having an unknown trip purpose. 

    List of papers
    1. Long-distance mode choice model estimation using mobile phone network data
    Open this publication in new window or tab >>Long-distance mode choice model estimation using mobile phone network data
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    2022 (English)In: Journal of Choice Modelling, E-ISSN 1755-5345, Vol. 42, article id 100337Article in journal (Refereed) Published
    Abstract [en]

    In this paper we develop two methods for the use of mobile phone data to support the estimation of long-distance mode choice models. Both methods are based on logit formulations in which we define likelihood functions and use maximum likelihood estimation. Mobile phone data consists of information about a sequence of antennae that have detected each phone, so the mode choice is not actually observed. In the first trip-based method, the mode of each trip is inferred by a separate procedure, and the estimation process is then straightforward. However, since it is not always possible to determine the mode choice with certainty (although it is possible in the majority of cases), this method might give biased results. In our second antenna-based method we therefore base the likelihood function on the sequences of antennae that have detected the phones. The estimation aims at finding a parameter vector in the mode choice model that would explain the observed sequences best. The main challenge with the antenna-based method is the need for detailed resolution of the available data. In this paper we show the derivation of the two methods, that they coincide in case of certainty about the chosen mode and discuss the validity of assumptions and their advantages and disadvantages. Furthermore, we apply the first trip-based method to empirical data and compare the results of two different ways of implementing it.

    Place, publisher, year, edition, pages
    Elsevier, 2022
    Keywords
    Demand model, Mode choice, Mobile phone network data, Travel behaviour, Long-distance travel
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-184941 (URN)10.1016/j.jocm.2021.100337 (DOI)000819919700002 ()
    Available from: 2022-05-13 Created: 2022-05-13 Last updated: 2024-03-14Bibliographically approved
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  • 48.
    Andersson, Angelica
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI Swedish National Road and Transport Research Institute, Sweden.
    Engelson, Leonid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Börjesson, Maria
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences. VTI Swedish National Road and Transport Research Institute, Sweden.
    Daly, Andrew
    ITS, University of Leeds, United Kingdom.
    Kristoffersson, Ida
    VTI Swedish National Road and Transport Research Institute, Sweden.
    Long-distance mode choice model estimation using mobile phone network data2022In: Journal of Choice Modelling, E-ISSN 1755-5345, Vol. 42, article id 100337Article in journal (Refereed)
    Abstract [en]

    In this paper we develop two methods for the use of mobile phone data to support the estimation of long-distance mode choice models. Both methods are based on logit formulations in which we define likelihood functions and use maximum likelihood estimation. Mobile phone data consists of information about a sequence of antennae that have detected each phone, so the mode choice is not actually observed. In the first trip-based method, the mode of each trip is inferred by a separate procedure, and the estimation process is then straightforward. However, since it is not always possible to determine the mode choice with certainty (although it is possible in the majority of cases), this method might give biased results. In our second antenna-based method we therefore base the likelihood function on the sequences of antennae that have detected the phones. The estimation aims at finding a parameter vector in the mode choice model that would explain the observed sequences best. The main challenge with the antenna-based method is the need for detailed resolution of the available data. In this paper we show the derivation of the two methods, that they coincide in case of certainty about the chosen mode and discuss the validity of assumptions and their advantages and disadvantages. Furthermore, we apply the first trip-based method to empirical data and compare the results of two different ways of implementing it.

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  • 49.
    Andersson, Anja
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Logistic process models for Swedtrac2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Detta examensarbete har utförts hos Swedtrac Trafik AB som är ett dotterbolag till Swedtrac AB. Swedtrac Trafik AB har trafikutövartillstånd och erbjuder utbildningar inom alla trafiksäkerhetsrelaterade delar av järnvägsverksamheten. Företaget har också verksamhet som löser kundernas transportbehov. Swedtrac Trafik AB baserar sin verksamhetsutveckling på processer vilket innebär att en processorienterad verksamhetsstyrning behövs för att klara dagens allt intensivare konkurrens på en global marknad. Därför är en initial processmall nödvändig. Syftet med detta examensarbete är att kartlägga nuvarande processer och göra en processmall/ett flödesschema från kundbeställning till slutprodukt samt ge en klar bild över var i processerna det finns möjlighet till effektivisering. Detta arbete är en studie av företagets processer med utvald processkartläggningsmetod. I metoden ingår studiebesök, telefon- grupp- och personlig intervju. Resultatet från dessa sammanställningar ger en djupare insyn i den nuvarande processen. Vid processkart-läggningen utgår arbetet från två vinklar: den ena är en ”as-is” process (swim lane chart) som utifrån beskrivningar från avdelningarnas intervjuer har ritats upp ett flöde över nuläget. Den andra är en ”to-be” process där problem som hittas i nulägesflödet har getts förslag på åtgärder. Processkarläggningen bygger på en SS-modell(sjustegsmodell). Varje steg bidrar till processmallen och har sitt eget syfte, mål och ett centralt värde för processkartläggningen. Resultatet består av två processmallar samt förbättringsförslag för nuläget och för framtiden. Förbättringsförslagen baseras på en processanalys av ”as-is” och ”to-be” processen. Processmallarna konstrueras med hjälp av modelleringsspråket ”BPMN”. Genom att jämföra de två processerna kan problem och förbättringsmöjligheter identifieras. När onödiga aktiviteter eliminerats och icke värdeskapande aktiviteter ändrats till värdeskapande, leder det till en minskning av administrativa kostnader samt att processens förmåga och effektiviteter förbättras. Detta innebär att processen kommer att utvecklas till en mer värdeskapande process.

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  • 50.
    Andersson, Dan
    Linköping University, Department of Management and Economics. Linköping University, The Institute of Technology.
    Third Party Logistics: Outsourcing Logistics in Partnerships1997Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The purpose of this dissertation is to contribute the body of knowledge of the outsourcing of logistics services in integrated relationships between a shipper ( e.g. a manufacturer) and a logistics service provider (e.g. a transport firm).

    My two studies cover the scope of third-party logistics and the interaction between the shipper and the service provider as well as the set-up of the partnerships. The focus of the dissertation could be expressed by the following questions:

    • Why do service buyers outsource logistics activities in the form of partnerships?

    • What are the long-term effects of logistics partnerships?

    • How are the effects of the logistics partnerships achieved?

    • Which factors influence the success of a logistics partnership?

    The method used has been a combination of four case studies and surveys of 47 European shippers and 59 US shippers. The empirical material has been analysed primarly by the use of transaction cost theory.

    Expected positive cost and service effects are important driving forces for the outsourcing of logistics. Linked to the cost aspects is also a desire to reduce investments. It could be a question of transforming fixed costs to variable, or to facilitate fast and radical restructuring of supply chains. Finally one of the single most important driving forces is the shipper's ambition to concentrate on core business.

    Logistics partnerships have been observed to have a positive effect on the following four areas at the shippers: cost, service, restructuring of supply chains, and control. The shippers believe that efficient operations, economies of scale and scope, and provider knowledge, have had positive effects on costs and service. A structural change could be achieved in a short time, as the shipper has to make only small investments in the distribution system, which can facilitate greater changes, also gaining the shipper flexibility in capacity. By outsourcing logistics activities it might also be possible to improve the measurability of cost and service performance.

    The success of logistics partnerships will, according to the shippers' opinions, be positively influenced by well-defined requirements and procedures, and by communication on all levels. From an operational point of view, the success of logistics partnerships is positively influenced by a low level of uncertainty and/or a high dedication of resources used.

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