Hide menu

Current Research

In the Traffic Systems group we have the following ongoing research areas/projects:

Public transport and improved railway system performance (see also Kajt):

  • Capacity4Rail
  • Robust timetables for railway traffic
  • Efficient planning of railway infrastructure maintenance
  • Planning algorithms for an integrated paratransit service
  • Integrating charging infrastructure and public transport planning

Transport modelling based on large scale sensor data (see also Transport Analytics Lab):

  • Mobile Millennium Stockholm (MMS)
  • Mobile Network Data in Future Transport Systems (MOFT)

Traffic modelling, traffic engineering and ITS:

  • Better Estimations of Energy use and Emissions when Analyzing Traffic (BE3AT)
  • Transport for sustainable urban development – integrated modelling of walk, cycle and public transport
  • Trialling and comparing smartphone based travel data collection with paper-and-pencil method (SPOT)
  • Microscopic simulation of a multimodal public transport interchange station
  • DEPEND – Development of a research and evaluation platform for environment-related driver assistance systems
  • Cooperative systems
  • Efficient public transport and economic effects of infrastructure investments



Participants: Martin Joborn, Pavle Kecman and Anders Peterson.

Capacity4Rail (C4R) is a large EU project, where LiU, in close co-operation with the Swedish Transport Administration (Trafikverket), is responsible for a work package entitled “Simulation and models to evaluate enhanced capacity (infrastructure and operations)”. The aim of C4R is to provide an overall increase in railway capacity by developing a holistic view on the railway as a system of interacting technical components driven by customer demand. In our work package we focus on simulation and mathematical modelling as methods for evaluating capacity enhancements. Modelling and simulation tools are currently used to assess the performance of the existing networks under different operational circumstances. The tools can be used to analyse and evaluate capacity of infrastructure and to support the design of new traffic systems. Furthermore, such methods and models can improve the timetable planning and operational processes. The aim of this task is to evaluate the existing tools for their suitability to assess and improve capacity utilization. The models will be reviewed and improved with the aim of demonstrating the innovations in this project. Modelling and simulation will be used to demonstrate the impact on capacity of both infrastructure and operations innovations.

The project is associated to KAJT, Capacity in the Railway Traffic System, which is a research program for improved railway system performance, see www.kajt.org.

Partners: The Swedish Transport Administration.
Financed by: The European Commission (7th Framework Program) and Swedish Transport Administration.
Contact: Pavle Kecman


Robust timetables for railway traffic

Participants: Emma Andersson, Fahimeh Khoshniyat, Anders Peterson and Johanna Törnquist Krasemann.

A growing demand for railway transportation observed in most Western countries has resulted in a capacity insufficiency where even a small disturbance of one single train can have a significant impact on other trains. This must be met by sufficient timetable margins and the challenge is to place these margins in an appropriate way. We call this to design robust timetables. The Swedish Transport Administration and SJ have also stated the need for methods which can compute robust timetables and create an improved feed-back loop between the timetabling phase and the real-time traffic management.

Our project aims at developing and evaluating such a method based on optimization techniques, with the purpose to increase the reliability and punctuality of the Swedish railway traffic. Two main approaches address the robustness in critical points, and travel-time dependent headways, respectively.

By the developed methods it will be possible to analyze and evaluate how and in what form headway times in combination with various types of running time supplements should be added to the timetable. It is hereby important to ensure that the added time margin can be used in a flexible way during the journey and not omitted by, for example, a scheduled crossing. The introduced robustness should be related to its associated costs, and a possibly increased travel time. The project is associated to KAJT, Capacity in the Railway Traffic System, which is a research program for improved railway system performance, see www.kajt.org.

Partners: The Swedish Transport Administration and SJ AB.
Financed by: Swedish Transport Administration, VINNOVA and SJ AB
Contact: Anders Peterson


Efficient planning of railway infrastructure maintenance

Participants: Martin Joborn, Tomas Lidén.

Efficiency in the public and freight transportation systems is of crucial importance for a society. Railways can offer high capacity and relatively low environmental impact, but require that several technical systems like the track, power distribution, safety, telecommunications and trains are tuned and operate well. Disturbances in any of these systems will degrade the service level. Moreover, failures or degradation in one may cause damages in the others. This is particularly true for track, trains and power distribution. Thus railway maintenance is crucial and constitutes a large amount of public spending.

The maintenance tasks must be coordinated with the train traffic. Equipment, parts, work crew and machines must be located, transported and scheduled efficiently. Small routine tasks (like inspections) should be coordinated with larger activities. Special weather conditions (snow, wet leaves) require special handling, sometimes limiting the train traffic. The technical degradation and the effects of maintenance must be measured and calculated. Hence the planning problems are many, complex and concern many different time scales. Furthermore they involve many stakeholders like infrastructure management, traffic control, train operators and different contractors who work in an increasingly deregulated economy.

The aim of this project is to develop methods and mathematical models to solve crucial planning and scheduling problems concerning railway infrastructure maintenance, preferably coordinated with the train traffic. The ambition is that these methods and models should be possible to put in practical use. If so, major enhancements regarding solution quality, response times and efficiency are envisioned.

Partners: Work performed as part of KAJT
Financed by: Swedish Transport Authority
Contact: Tomas Lidén


  • Tomas Lidén, Thomas Kalinowski, Hamish Waterer, 2018. Resource considerations for integrated planning of railway traffic and maintenance windows. Journal of Rail Transport Planning & Management. DIVA.
  • Tomas Lidén, Martin Joborn, 2017. An optimization model for integrated planning of railway traffic and network maintenance. Transportation Research Part C: Emerging Technologies. DIVA.
  • Tomas Lidén, 2016. Towards concurrent planning of railway maintenance and train services Linköping Studies in Science and Technology. Thesis 1746, ISSN 0280-7971, at Diva
  • Tomas Lidén, Martin Joborn, 2016. Dimensioning windows for railway infrastructure maintenance: Cost efficiency versus traffic impact Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 6, nr 1, 32-47, at Diva
  • Tomas Lidén, 2015, Railway Infrastructure Maintenance - A Survey of Planning Problems and Conducted Research, Transportation Research Procedia Volume 10, Pages 574–583, available at Diva
  • Tomas Lidén, 2014, Survey of railway maintenance activities from a planning perspective and literature review concerning the use of mathematical algorithms for solving such planning and scheduling problems, DIVA.



Planning algorithms for an integrated paratransit service

Participants: Carl Henrik Häll and Marcus Posada

This project investigates how paratransit systems for transportation of elderly and disabled can be combined with fixed-route public transport in order to create a more efficient transportation service, while offering a new public transport service to the general public. The project aims to develop a methodology for operational planning for an integrated paratransit system, in which travelers can travel some parts with the demand responsive service and some with fixed-route services. Designing integrated trips with the efficiency of the publicly financed paratransit service in focus, gives large combinatorial problems to be solved in order to decide which trips to perform as “integrated trips”, where interchanges between transport modes should be made, which vehicle will perform the assignments etc. in order to find the best overall vehicle routes. This also means that the planning problem is very computationally demanding. We work with this problem both using explicit optimization formulations as well as with heuristic methods that are of more practical use for real cases.

Based on the aging population, there is every reason to believe that the demand for, and need of, transportation services will increase substantially in the near future. Due to this, there is great reason to review the opportunities for efficiency improvements available in this area. The impact of the project results are expected to contribute to increased efficiency of paratransit services.

Partners: Norwegian University of Science and Technology, Planit Sweden AB and Västtrafik
Financed by: VINNOVA (Swedish Governmental Agency for Innovation Systems).
Carl-Henrik Häll



Integrating charging infrastructure and public transport planning

Participants: Carl Henrik Häll, Nils-Hassan Quttineh and Joakim Ekström

Full electric and hybrid electric busses are currently being tested in many European cities. Few examples, however, exists of large-scale introduction of such busses. To be able to move from smaller demonstration projects to large-scale applications, the planning of charging infrastructure needs to be integrated into the public transport planning. This is required in order to fully take advantage of electric busses while having a cost efficient deployment of charging infrastructure.

This project encourages and facilitates the introduction of rechargeable vehicles in public transport by contributing to the development of integrated planning methods for the public transport system and its charging infrastructure. Networks and timetables should be planned in a way that provides an effective usage of the charging infrastructure and also enables usage of electric power for as long distances as possible or in priority areas. The project demonstrates how integrated planning of charging infrastructure, networks and timetables can be done, and the effects of integrated planning are evaluated.

Partners: City of Gothenburg, Keolis, Nettbuss, Skånetrafiken, Stockholm County Council and Västtrafik
Financed by: The Swedish Energy Agency
Contact: Carl-Henrik Häll



Mobile Millennium Stockholm (MMS)

Participants: Andreas Allström, Joakim Ekström, Rasmus Ringdahl, Clas Rydergren and David Gundlegård (MT)

The Mobile Millennium Stockholm (MMS) project is an initiative to establish a platform for research and development within real-time traffic information and traffic management in Sweden. The need for accurate real-time traffic information is growing in almost all big cities around the world. One of these cities is Stockholm, recently named as the fifth most congested city in Western Europe. The purpose of the project is to assimilate the knowledge gained from the Mobile Millennium project at University of California, Berkeley and develop new methods for data fusion, one of the most challenging research areas in the transport community today. The data fusion methods will utilize the potential of each data source in order to improve estimations and predictions of the traffic state.

This project is part of Transport Analytics Lab.


  • Allström A, Bayen A M, Fransson M, Gundlegård D, Patire A D, Rydergren C, et al. Calibration Framework based on Bluetooth Sensors for Traffic State Estimation Using a Velocity based Cell Transmission Model. 17th Meeting of the EURO Working Group on Transportation, EWGT2014, 2-4 July 2014, Sevilla, Spain. Elsevier; Transportation Research Procedia. 2014;3:972-981.
  • Allström A, Gundlegård D, Rydergren C. Evaluation of travel time estimation based on LWR-v and CTM-v : A case study in Stockholm. In: 15th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2012: . ITSC 2012: 15th International IEEE Conference on Intelligent Transportation Systems, Anchorage, AK, USA, 16-19 September 2012. Piscataway, N.J, USA: IEEE; 2012. p. 1644-1649. IEEE International Conference on Intelligent Transportation Systems-ITSC.

Partners: Project partners are KTH, Trafik Stockholm and Sweco.
Financed by: Swedish Transport Administration
Contact: David Gundlegård



Mobile Network Data in Future Transport Systems (MOFT)

Participants: Clas Rydergren, David Gundlegård (MT) and Di Yuan (MT)

The availability of advanced mobile devices at a very low cost generates massive amounts of signaling data in cellular networks that can be turned into spatio-temporal observations of human mobility. These observations will fundamentally change how we understand human travel behavior and how to operate and optimize our transport systems. Better estimation of travel demand, mode choice and route choice is central for a key functionality of future smart cities with dynamic and integrated multimodal control of the transport system.

The project will focus on a number of unexplored applications of dynamically estimated mobility patterns. The applicatrions are highly prioritized by the end users of the project: 1) Public transport planning, 2) Traffic management, 3) ex-post evaluation of infrastructure investments, 4) estimation of long distance travels, and 5) ride sharing potential of Mobility as a Service (MaaS).

This project is part of Transport Analytics Lab.

Partners: Ericsson, SICS, Trafikverket, City of Stockholm, Sweco, Tele2, SJ, Nobina, Samtrafiken.
Financed by: Vinnova
Contact: Clas Rydergren



Better Estimations of Energy use and Emissions when Analyzing Traffic (BE3AT)

Participants: Joakim Ekström and Johan Olstam

Traffic forecasting models are important tools when planning for future infrastructure investments or traffic management strategies in urban areas. The output from such models, in terms of travel times and flows, are commonly used as input to energy use and emission models, which will provide a prediction of emission levels on individual streets in the traffic network. Traffic flows, travel times and emissions are in turn vial information when evaluating proposed infrastructure projects.

For large scale networks/regions and long term prognoses, traffic analysis are commonly conducted using an aggregated description of the traffic flow (macroscopic traffic assignment models). These traffic analysis tools have limited possibility to correctly model how traffic queues are distributed in the network, and this makes it difficult to correctly describe how travel times and emissions are affected by changes in the traffic system. This project focuses on improving traffic link and intersection modeling in traffic analysis tools (macroscopic models) which are used for large regions. The purpose is to improve the estimation of travel times, energy use and emissions when performing long term traffic prognoses.

Partners: The Swedish National Road and Transport Research Institute (VTI)
Financed by: The Swedish Energy Agency.
Contact: Joakim Ekström



Transport for sustainable urban development – integrated modelling of walk, cycle and public transport

Participants: Gerasimos Loutos, Andreas Tapani and Clas Rydergren

The planning of future regional transportation systems requires models where all modes are integrated. Today's planning models often lack important connections between the modes. In comparison with the models used for the planning related to car traffic, models for the planning of public transport, walking and cycling are usually simplistic, and often lack important policy variables. The project aim is to contribute to sustainable regional transport through the development of models for planning and evaluation of walking and cycling as well as their modal connections to other modes of transport, especially public transport. The purpose is to improve on the current state of the art in urban and regional planning modelling, improving specifically trade-offs related to market shares for public transport, walking and cycling.

Partners: VTI
Financed by: Swedish Transport Administration
Contact: Gerasimos Loutos



Trialling and comparing smartphone based travel data collection with paper-and-pencil method (SPOT)

Participants: Clas Rydergren and Andreas Allström (Sweco/LiU)

Currently, there is a great need of new methods for collecting travel data. Traditional methods used for collecting travel data has a lot of drawbacks and at the same time the models used to analyze the transport system require more and more detailed data of high quality. One of the main barriers of collecting accurate and detailed disaggregate activity-travel data is the limitation of the method used to follow the travellers’ choices through space and time. However, in the recently published report Nya indatakällor för trafikprognoser, written by Sweco, Linköpings University and KTH, GPS devices was identified as one of the most interesting technologies to investigate further. Given that GPS devices and smartphones with GPS functionality are now becoming more wide spread, it is easier to capture the users’ spatial movement behaviour over time. This is also mentioned in Trafikverket’s reportUtveckling av samhällsekonomiska metoder och verktyg, effektsamband och modeller inom transportområdet. The use of web-interactive survey, combined with GIS mapping of tracked movements, means that the complexity of individual travel-making decision processes are now much more observable and analysable. Because of this, it is believed now that GPS-based data collection is one of the better alternatives in in travel behaviour research, compared with traditional survey methods. Earlier studies show that a GPS-based data collection has a great potential to solve the problems related to the estimation of distance/travel time, geographic coding of departure /destination locations and forgotten trips. It will also provide a more detailed data set, something that is essential for the next generation of transport models.

Partners: Sweco and KTH
Financed by: Swedish Transport Administration
Contact: Clas Rydergren



Microscopic simulation of a multimodal public transport interchange station

Participants: Fredrik Johansson, Anders Peterson and Andreas Tapani

The number of people travelling by public transport in Sweden is predicted to increase the coming decades; the public transport sector aims to double the number of travelers from 2006 to 2020. This will lead to a higher load on the central point of the local public transport system, the multimodal interchange station. A large part of the subjective generalized travel cost of a public transport trip is concentrated to the change of transport, which further emphasizes the need of a well-functioning interchange station.

In this project we evaluate the proposed design of a new interchange station by use of microscopic simulation of pedestrians. We use an adaption of the social force model to describe pedestrian movements, and develop related measures to describe the efficiency imposed by the design.

Partners: Swedish National Road and Transport Research Institute (VTI), Östgötatrafiken and Linköpings kommun
Financed by: Swedish Transport Administration
Contact: Fredrik Johansson



DEPEND – Development of a research and evaluation platform for environment-related driver assistance systems

Participants: Johan Olstam and Roya Elyasi-Pour

The aim of the project is to develop a research and evaluation platform for environment-related driver assistance systems. The platform is being developed by linking together models and tools for studying driver behaviour (driving simulators, field operational tests (FOT), acceptance studies, etc), the traffic system (traffic simulation) and environmental impacts (fuel consumption and emissions models). The project is a collaborative project between VTI, Linköping University and Scania.The project includes a doctoral student who divides her time between VTI and Linköping University.

Financed by: FFI – Transport Efficiency research program administrated by VINNOVA.
Contact: Roya Elyasi-Pour



Cooperative systems

Participants: Andreas Tapani and Ellen Grumert

Cooperative systems are expected to have a great impact on the road traffic of the future. Up until now much of the development of cooperative systems has taken place from a traffic safety perspective. ITS based on communication between vehicles and between vehicles and the infrastructure, however, has great potential to contribute to greater energy efficiency and less environmental impact. The aim of the project is to use simulation to quantify this potential for environmental improvements in different kinds of cooperative systems and thereby support the Swedish Transport Administration’s future prioritisations in this area.

Partners: VTI and KTH
Financed by: Swedish Transport Administration
Contact: Ellen Grumert



Efficient public transport and economic effects of infrastructure investments

Participant: Johan Holmgren (QL)

This research has two parts. In the first part the performance of the public transport system is studied. This involves studying the demand for public transport that is generated under different levels of pricing, service and subsidization. An important part of the project is to determine if the public spending on public transport is efficient in terms of how much public transport service is provided and if not, how this can be remedied. In the second part we examine the interrelationship between investments in transport infrastructure and economic development. An important part of this research is to separate the effects of relocated economic activities due to changes in transport costs from new economic activity generated by an investment.

Financed by: Swedish Transport Administration (part 2)
Contact: Johan Holmgren


Page manager: clas.rydergren@liu.se
Last updated: Tue Mar 06 13:45:14 CET 2018