liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 56) Show all publications
Grumert, E., Bernhardsson, V., Ekström, J., Gundlegård, D., Ringdahl, R. & Tapani, A. (2019). Variabla hastighetsgränser för Stockholms motorvägsnät: Effekter av alternativa algoritmer och möjligheter till styrning genom skattade trafiktillstånd. Linköping: Swedish National Road and Transport Research Institute (VTI)
Open this publication in new window or tab >>Variabla hastighetsgränser för Stockholms motorvägsnät: Effekter av alternativa algoritmer och möjligheter till styrning genom skattade trafiktillstånd
Show others...
2019 (Swedish)Report (Other academic)
Alternative title[en]
Variable speed limits for Stockholm’s urban motorways : Effects of differentalgorithms and the possibility to control by the use of estimated traffic states
Abstract [sv]

Variabla hastighetsgränser är väl utbrett på Stockholms stadsnära motorvägar och en del av Stockholms Motorway Control System (MCS). Målet med dagens system är att minska risken för olyckor och följdolyckor vid låga hastigheter, trafikstockningar m.m. Detta görs genom att mäta medelhastigheten med hjälp av fasta detektorer och uppdatera hastigheten som visas på variabla meddelandeskyltar utifrån rådande trafiktillstånd. I och med att efterfrågan på resor i Stockholm under rusningstid överstiger den tillgängliga kapaciteten i vägnätet är behovet av ett effektivt trafiksystem stort. Variabla hastighetsgränser kan bidra till ökad framkomlighet, men då dagens system har som målsättning att öka säkerheten är effekter som leder till ökad framkomlighet begränsade. Dessutom finns det i dagens system ett stort beroende av fungerande detektorer som mäter trafiktillståndet så korrekt som möjligt för att valet av hastighet ska kunna bestämmas på ett effektivt sätt.

Syftet med den här rapporten är att undersöka alternativa styralgoritmer för att bestämma variabla hastighetsgränser på Stockholms motorvägsnät. Målet är att öka framkomligheten jämfört med dagens system. Två olika sträckor med olika komplexitet, trafiksituation och problematik studeras. Valet av studerade styralgoritmer för de olika sträckorna väljs för att på bästa sätt motverka den problematiken som uppstår på de specifika sträckorna. Därmed kan val av algoritmer komma att skilja sig åt beroende på sträcka. I projektet utvärderas också om estimering av trafiktillståndet kan användas för att förbättra informationsflödet till algoritmerna då detektorer inte fungerar som de ska eller helt saknas, vilket i sin tur kan leda till förbättrad anpassning av de variabla hastighetsgränserna. Detta görs av för en av de studerade sträckorna. Styralgoritmerna utvärderas med mikroskopisk trafiksimulering och metoden utvecklad i projektet Mobile Millenium Stockholm (MMS), som bygger på en makroskopisk trafikflödesmodell och Kalman filtrering, används för estimering av trafiktillståndet.

Resultatet visar att det finns styralgoritmer med potential att öka framkomligheten. Valet av styralgoritm är dock beroende av typ av trafiksituation, vägdesignens komplexitet och trafikförhållanden på vägen. Det betyder att olika styralgoritmer kan prestera olika bra beroende på vilken vägsträcka man studerar. Vidare är estimering av trafiktillståndet användbart vid förlorad information på grund av icke-fungerande detektorer eller som komplement till detektorer för att minska mängden stationär utrustning.

Abstract [en]

Variable speed limits are commonly used on Stockholm’s urban motorways, and it is part of the Stockholm Motorway Control System (MCS). The goal of today’s system is to reduce the risk of accidents during congested conditions, traffic jams etc. This is done by updating the speed limits shown on variable message signs based on a measured average speed at fixed detectors. As the demand for travel in Stockholm during peak-hours exceeds the available capacity in the road network, the need for an efficient traffic system is high. Variable speed limit systems have the possibility to contribute to increased efficiency, but since today’s system aims to increase safety, effects that lead to increased efficiency are limited. Further, in todays’ variable speed limit systems there are a large dependency of precise and available measurements from stationary detectors to be able to display speed limits that reflects the current traffic conditions. The purpose of this report is to investigate alternative control algorithms to decide on the variable speed limits to be displayed at variable message signs on the urban motorway of Stockholm.

The goal is to increase efficiency compared to today's system. Two different road stretches with different complexity and different traffic conditions, resulting in two different types of congestion, are studied. Thereby, the studied control algorithms on the two road stretches are chosen based on the possibility of solving a specific problematic traffic situation in the best way. Hence, the studied control algorithms might differ for the two road stretches. Furthermore, for one of the roads stretches it is investigated if estimation of the traffic state can be used as input to the control algorithm as a complement to missing and erogenous measurements from stationary detectors in order to improve the calculations of the variable speed limits. The control algorithms are evaluated with microscopic traffic simulation and the method developed in the project Mobile Millenium Stockholm (MMS), using a macroscopic traffic flow model together with a Kalman filter, is used for estimation of the traffic state.

The result shows that there are control algorithms with the potential to increase efficiency. However, the choice of suitable control algorithm for improving traffic efficiency is dependent on the traffic situation, the complexity of the road design and the traffic conditions. Furthermore, estimation of the traffic state is useful when information is lost due to malfunctioning detectors or as a complement to reduce the amount of stationary detectors.

Place, publisher, year, edition, pages
Linköping: Swedish National Road and Transport Research Institute (VTI), 2019. p. 52
Series
VTI Rapport, ISSN 0347-6030, E-ISSN 0347-6030 ; 1006
Keywords
Traffic control, variable speed limits, predictive control, microscopic traffic simulation, macroscopic traffic simulation, Trafikstyrning, variabla hastighetsgränser, prediktiv styrning, mikroskopisk trafiksimulering, makroskopisk trafiksimulering
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-158028 (URN)
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-06-24Bibliographically approved
Grumert, E., Tapani, A. & Ma, X. (2016). Evaluation of Four Control Algorithms Used in Variable Speed Limit Systems. In: TRB 95th Annual Meeting Compendium of Papers: . Paper presented at Transportation Research Board 95th Annual Meeting, Washington D.C., USA, January 10-14, 2016. Washington: Transportation Research Board, Article ID 16-2880.
Open this publication in new window or tab >>Evaluation of Four Control Algorithms Used in Variable Speed Limit Systems
2016 (English)In: TRB 95th Annual Meeting Compendium of Papers, Washington: Transportation Research Board , 2016, article id 16-2880Conference paper, Published paper (Refereed)
Abstract [en]

Control algorithms used for deciding on the speed limits in variable speed limit systems are crucial for the performance of the system. Today, many of the control algorithms used are based on fixed thresholds in speed and/or flow for lowering and increasing the speed limit. The algorithms are not necessarily reflecting the conditions on the road, which might lead to low traffic efficiency. Our hypothesis is that by use of a simple and efficient control algorithm that is better in reflecting the conditions on the road, both traffic efficiency and traffic safety could be increased. In this study, four control algorithms used in variable speed limit systems, and fulfilling the above criteria, are evealuted through microscopic traffic simulation. Performance indicators related to traffic safety, traffic efficiency and environmental impacts are presented. The results show that the design of, and the objective with, the control algorithm have a great impact on the performance. Moreover, the time needed for incident detection, the duration of and the size of the speed limit reduction and the location of the congestion are of importance for the performance of the control algorithms. These results will be of importance for design and implementation of future efficient variable speed limit systems.

Place, publisher, year, edition, pages
Washington: Transportation Research Board, 2016
Keywords
variable speed limit systems, control algorithms, microscopic traffic simulation
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-129518 (URN)
Conference
Transportation Research Board 95th Annual Meeting, Washington D.C., USA, January 10-14, 2016
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2016-06-29Bibliographically approved
Strömgren, P., Olstam, J. & Tapani, A. (2015). A Model for Traffic Simulation of Flared Rural Road Intersections. Paper presented at ISTS 2014, the 4thInternational Symposium of Transport Simulation, Ajaccio, Corsica France, 1-4 June 2014. Transportation Research Procedia, 6(2015), 239-258
Open this publication in new window or tab >>A Model for Traffic Simulation of Flared Rural Road Intersections
2015 (English)In: Transportation Research Procedia, ISSN 2352-1465, Vol. 6, no 2015, p. 239-258Article in journal (Refereed) Published
Abstract [en]

This paper presents a micro-simulation model that takes flared design of rural intersections into consideration. The intersection model is designed with input parameters that describe the geometric conditions of the flare. The behavior model includes both a traditional gap-acceptance sub-model and a passage model for modelling of vehicles’ possibility to pass other vehicles using the flare. The intersection model developed has been implemented in the traffic micro simulation model RuTSim. The gap-acceptance part of the model has been calibrated using data for stop and yield 3-way intersections. The validation was performed by using video recordings to calculate delay for the yield regulated intersection and time in queue and service time for the stop regulated intersection. The results from the validation simulations correspond well with the empirical validation data. The effect of the flare on delay has been studied by using 3 different intersection lay-outs and different levels of minor and major flow. The result shows that the delay is decreasing with increasing intersection radius.

Keywords
micro simulation, intersection, non-discrete, flare, gap-acceptance, rural
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-120781 (URN)10.1016/j.trpro.2015.03.019 (DOI)000380490100019 ()
Conference
ISTS 2014, the 4thInternational Symposium of Transport Simulation, Ajaccio, Corsica France, 1-4 June 2014
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Available from: 2015-08-25 Created: 2015-08-25 Last updated: 2019-07-05
Grumert, E., Ma, X. & Tapani, A. (2015). Analysis of a cooperative variable speed limitsystem using microscopic traffic simulation. Transportation Research Part C: Emerging Technologies, 52, 173-186
Open this publication in new window or tab >>Analysis of a cooperative variable speed limitsystem using microscopic traffic simulation
2015 (English)In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 52, p. 173-186Article in journal (Refereed) Published
Abstract [en]

Variable speed limit systems where variable message signs are used to show speed limits adjusted to the prevailing road or traffic conditions are installed on motorways in many countries. The objectives of variable speed limit system installations are often to decrease the number of accidents and to increase traffic efficiency. Currently, there is an interest in exploring the potential of cooperative intelligent transport systems including communication between vehicles and/or vehicles and the infrastructure. In this paper, we study the potential benefits of introducing infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits in variable speed limit systems. We do this by proposing a cooperative variable speed limit system as an extension of an existing variable speed limit system. In the proposed system, communication between the infrastructure and the vehicles is used to transmit variable speed limits to upstream vehicles before the variable message signs become visible to the drivers. The system is evaluated by the means of microscopic traffic simulation. Traffic efficiency and environmental effects are considered in the analysis. The results of the study show benefits of the infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits for variable speed limit systems in the form of lower acceleration rates and thereby harmonized traffic flow and reduced exhaust emissions.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Cooperative systems;Intelligent transport systems;Infrastructure to vehicle communication;Variable speed limit;Microscopic traffic simulation; Emission model
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-115013 (URN)10.1016/j.trc.2014.11.004 (DOI)000352252400012 ()
Available from: 2015-03-06 Created: 2015-03-06 Last updated: 2018-04-10
Wiklund, M., Carlsson, A., Eriksson, O., Olstam, J. & Tapani, A. (2015). Effects of desired speeds for queuing and delay on single-lane road segments. Paper presented at 2015/08/24. Transportmetrica A: Transport Science, 11(8), 716-728
Open this publication in new window or tab >>Effects of desired speeds for queuing and delay on single-lane road segments
Show others...
2015 (English)In: Transportmetrica A: Transport Science, ISSN 2324-9935, Vol. 11, no 8, p. 716-728Article in journal (Refereed) Published
Abstract [en]

To improve road safety on parts of the road network carrying low traffic volumes, road designs are proposed including single-lane road segments and periodic overtaking lanes. These roads have been proven to contribute to substantial benefits in terms of road safety. However, overtaking of slower vehicles is only possible on segments including an overtaking lane and not on the single-lane road segments. Driver and vehicle heterogeneity resulting in differences in desired speeds are consequently decisive for the traffic performance. Sufficient quality of service is relying on an appropriate design and distribution of single-lane segments and overtaking lanes. In this paper, we study the effect of the desired speed distribution on traffic performance on single-lane road segments. Expressions are derived for the travel time, delay and percent time spent following. The derived expressions link the desired speed distribution, the single-lane segment length and the traffic flow to the resulting traffic performance. The results are verified through comparison with measures based on microscopic traffic simulation. The conclusion is that there is a good agreement between derived measures and simulation results. The derived measures should therefore not only be of theoretical interest, but also of practical use to estimate traffic performance on single-lane road segments.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2015
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-120782 (URN)10.1080/23249935.2015.1066462 (DOI)000360555900004 ()
Conference
2015/08/24
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Available from: 2015-08-25 Created: 2015-08-25 Last updated: 2017-12-04
Johansson, F., Peterson, A. & Tapani, A. (2015). Waiting pedestrians in the social force model. Physica A: Statistical Mechanics and its Applications, 419, 95-107
Open this publication in new window or tab >>Waiting pedestrians in the social force model
2015 (English)In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 419, p. 95-107Article in journal (Refereed) Published
Abstract [en]

Microscopic simulation of pedestrian traffic is an important and increasingly popular method to evaluate the performance of existing or proposed infrastructure. The social force model is a common model in simulations, describing the dynamics of pedestrian crowds given the goals of the simulated pedestrians encoded as their preferred velocities. The main focus of the literature has so far been how to choose the preferred velocities to produce realistic dynamic route choices for pedestrians moving through congested infrastructure. However, limited attention has been given the problem of choosing the preferred velocity to produce other behaviors, such as waiting, commonly occurring at, e.g., public transport interchange stations. We hypothesize that: (1) the inclusion of waiting pedestrians in a simulated scenario will significantly affect the level of service for passing pedestrians, and (2) the details of the waiting model affect the predicted level of service, that is, it is important to choose an appropriate model of waiting. We show that the treatment of waiting pedestrians have a significant impact on simulations of pedestrian traffic. We do this by introducing a series of extensions to the social force model to produce waiting behavior, and provide predictions of the model extensions that highlight their differences. We also present a sensitivity analysis and provide sufficient criteria for stability. (C) 2014 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Social force model; Waiting pedestrians; Microscopic simulation
National Category
Civil Engineering
Identifiers
urn:nbn:se:liu:diva-113715 (URN)10.1016/j.physa.2014.10.003 (DOI)000347017300012 ()
Note

Funding Agencies|Swedish Transport Administration [TRV 2013/13329]

Available from: 2015-01-30 Created: 2015-01-29 Last updated: 2018-08-23
Jonkers, E., Carsten, O., Nellthorp, J., Olstam, J. & Tapani, A. (2014). Data and framework for scaling up. Leeds
Open this publication in new window or tab >>Data and framework for scaling up
Show others...
2014 (English)Report (Other academic)
Abstract [en]

The global aim of the ecoDriver project is to increase the fuel efficiency by 20% by optimising the driver-powertrain-environment feedback loop and delivering effective advice to drivers. In the course of the project, field experiments will take place with a wide range of vehicles — e.g. cars, light trucks and vans, medium and heavy trucks and buses — covering both individual and collective transport. The last step of the project (Sub Project 5; SP5) is to scale up the results from these tests and analyse costs and benefits for a number of futurescenarios.

The aim of SP5 is to predict the impact of the ecoDriver systems and solutions in the future, drawing on all the evaluations carried out in the project. With the results of SP5 it will be possible to make estimates about the costs and benefits of the suggested green driving support systems on a global (EU-27) level, both for society as a whole and for sub-groups like manufacturers and consumers. SP5 will construct a set of possible scenarios for the future depending on various road maps envisioned today. The predictions for future years will be made based on available data from within and outside of the project, and on advanced microscopic traffic modelling. SP5 takes the following steps to meet the objectives:

  • Collect data needed for scaling up and developing scenarios
  • Create a range of scenarios
  • Assess the network implications of green driving support systems for future networks
  • Predict the global impacts for a range of systems and scenarios
  • Carry out a cost benefit analysis for a range of systems and scenarios

This deliverable describes the data needs for each step. It also contains a description of the approaches proposed for the scenario building, the microscopic traffic simulations, the scaling up and the cost-benefit analysis.

Place, publisher, year, edition, pages
Leeds: , 2014. p. 30
Series
ecoDriver ; D51.1
National Category
Transport Systems and Logistics
Research subject
20 Road: Traffic engineering, 23 Road: ITS och traffic
Identifiers
urn:nbn:se:liu:diva-121209 (URN)
Projects
ecoDriver
Available from: 2014-11-25 Created: 2015-09-09 Last updated: 2016-05-17Bibliographically approved
Bång, K.-L., Olstam, J., Köhler, J., Wahlstedt, J., Andersson, J. & Tapani, A. (2014). Handbok för kapacitetsanalys med hjälp av simulering. Borlänge: Trafikverket
Open this publication in new window or tab >>Handbok för kapacitetsanalys med hjälp av simulering
Show others...
2014 (Swedish)Report (Other academic)
Abstract [sv]

Syftet med föreliggande handbok är att beskriva hur trafiksimulering kan användas som en alternativ metod eller komplement till analytiska metoder för att bestämma kapacitet och framkomlighet. Liksom metodbeskrivningarna i TRV2013/64343 är beskrivningarna avsedda att kunna användas för att med hjälp av trafiksimulering uppskatta effekterna av en given utformning i samband med planering, konsekvensanalys, projektering och drift av vägtrafikanläggningar. Simulering kan användas som ett komplement till de analytiska metoderna, eller som ersättning i fall som inte täcks av dessa metoder. Härigenom minskas risken för onödiga kostnader förorsakade av såväl över- som underkapacitet.

Place, publisher, year, edition, pages
Borlänge: Trafikverket, 2014. p. 118
Series
TRV ; TRV2013/79994
Keywords
Trafiksimulering, framkomlighet, kapacitet
National Category
Transport Systems and Logistics
Research subject
20 Road: Traffic engineering; 20 Road: Traffic engineering, 25 Road: Traffic theory; 20 Road: Traffic engineering, 21 Road: Traffic measurement and traffic analysis
Identifiers
urn:nbn:se:liu:diva-111816 (URN)
Available from: 2014-11-04 Created: 2014-11-04 Last updated: 2015-02-27Bibliographically approved
Johansson, F., Peterson, A. & Tapani, A. (2014). Local performance measures of pedestrian traffic. Public Transport, 6(1-2), 159-183
Open this publication in new window or tab >>Local performance measures of pedestrian traffic
2014 (English)In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 6, no 1-2, p. 159-183Article in journal (Refereed) Published
Abstract [en]

Efficient interchange stations, where travelers are changing lines and/or travel modes, are essential for the functionality of the whole public transport system. By studying pedestrian movements, the level of service and effectiveness imposed by the design of the interchange station can be evaluated. We address the problem by microsimulation, where a social force model is used for the phenomenological description of pedestrian interactions. The contribution of this paper is the proposal of measures describing the density, delay, acceleration and discomfort for pedestrian flows. Simulation experiments are performed for the movements in two canonical pedestrian areas, a corridor and a corridor intersection. Clearly, each of the four measures gives a description for how pedestrians impede each other, and hence for the efficiency at the facility. There is, however, different information provided by each measure, and we conclude that they all are well-motivated for quantifying the level of service in a pedestrian flow. We also illustrate the outcome for a railway platform, with two trains arriving in parallel.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2014
Keywords
Interchange stations, Microsimulation, Pedestrians, Social force model
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-109045 (URN)10.1007/s12469-013-0081-9 (DOI)
Available from: 2014-08-04 Created: 2014-08-04 Last updated: 2018-08-23Bibliographically approved
Grumert, E., Tapani, A. & Ma, X. (2013). Effects of a Cooperative Variable Speed Limit System on Traffic Performance and Exhaust Emissions. In: TRB 92nd Annual Meeting Compendium of Papers: . Paper presented at Transport Research Board 92nd Annual Meeting, 13-17 January 2013, Washington DC, USA.
Open this publication in new window or tab >>Effects of a Cooperative Variable Speed Limit System on Traffic Performance and Exhaust Emissions
2013 (English)In: TRB 92nd Annual Meeting Compendium of Papers, 2013Conference paper, Published paper (Refereed)
Abstract [en]

Variable Speed Limit Systems (VSLS) where variable message signs show speed limits based on traffic or road conditions exist on motorways in many countries. The purpose of the VSLS is to decrease the number of accidents while increasing efficiency of traffic system. Cooperative systems are a type of intelligent transport system that has received increasing interest lately. The central part of a cooperative system is communication between vehicles and/or vehicles and the infrastructure. In this paper, a cooperative systems extension of a VSLS is proposed and evaluated by means of microscopic traffic simulation. In the proposed cooperative VSLS, communication between the vehicles and the infrastructure is made available via a roadside unit communicating the speed limits to vehicles upstream on the road. Both aggregate and micro-scale emission models are used to estimate emission from vehicle states in traffic flow. The results of the study show that the cooperative VSLS has a potential to contribute to flow harmonization and to reduce environmental impacts. The emission estimates in the study are dependent on the emission models being applied.

Series
Transport Research Board 92nd Annual Meeting
Keywords
Exhaust gases; Intelligent transportation systems; Traffic flow; Traffic simulation; Variable speed limits; Vehicle to roadside communications; Vehicle to vehicle communications; Cooperative systems
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-92746 (URN)
Conference
Transport Research Board 92nd Annual Meeting, 13-17 January 2013, Washington DC, USA
Available from: 2013-05-20 Created: 2013-05-20 Last updated: 2015-03-06
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9635-5233

Search in DiVA

Show all publications