Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Macroscopic traffic simulations are widely used in the world in order to provide assistance in the traffic infrastructure development as well as for the strategic traﬃc planning. When studying a large traffic network macroscopic traffic simulation can be used to model current and future traffic situations. The two most common software used for traffic simulation in Sweden today are Emme and Visum, developed by INRO respective PTV.
The aim of the thesis is to perform a comparison between the software Emme and Visum with respect to the assignment of public transport, in other words how passengers choose their routes on the existing public transport lines. However, in order to make a complete software comparison the run-time, analysis capabilities, multi-modality, capacity to model various behavioural phenomena like crowding, fares etc. this will not be done in this comparison. It is of interest to study the differences between the two software algorithms and why they might occur because the Swedish Transport Administration uses Emme and the Traffic Administration in Stockholm uses Visum when planning public transport. The comparison will include the resulting volumes on transit lines, travel times, ﬂow through speciﬁc nodes, number of boarding, auxiliary volumes and number of transits. The goal of this work is to answer the following objective: What are the differences with modelling a public transport network in Emme and in Visum, based on that the passengers only have information about the travel times and the line frequency, and why does the differences occur?
In order to evaluate how the algorithms work in a larger network, Nacka municipality (in Stockholm) and the new metro route between Nacka Forum and Kungsträdgården have been used. The motivation for choosing this area and case is due to that it is interesting to see what differences could occur between the programs when there is a major change in the traffic network.
The network of Nacka, and parts of Stockholm City, has been developed from an existing road network of Sweden and then restricted by "cutting out" the area of interest and then removing all public transportation lines outside the selected area. The OD-matrix was also limited and in order not to loose the correct ﬂow of travellers portal zones was used to collect and retain volumes.
To ﬁnd out why the differences occur the headway-based algorithms in each software were studied carefully. An example of a small and simple network (consisting of only a start and end node) has been used to demonstrate and show how the algorithms work and why volumes split differently on the existing transit lines in Emme and Visum. The limited network of Nacka shows how the different software may produce different results in a larger public transport network.
The results show that there are differences between the program algorithms but the signiﬁcance varies depending on which output is being studied and the size of the network. The Visum algorithm results in more total boardings, i.e. more passengers have an optimal strategy including a transit. The algorithms are very similar in both software programs, since they include more or less parts of the optimal strategy. The parameters used are taken more or less into consideration in Emme and Visum. For example Visum will ﬁrst of all focus on the shortest total travel time and then consider the other lines with respect to the maximum waiting time. Emme however, ﬁrst focuses on the shortest travel time and then considers the total travel time for other lines with half the waiting time instead of the maximum wait time. This results in that less transit lines will be attractive in Emme compared to Visum. The thesis concludes that varying the parameters for public transport in each software algorithm one can obtain similar results, which implies that it is most important to choose the best parameter values and not to choose the "best" software when simulating a traffic network.
2014. , 104 p.