31st March 2009One-day Conference on Traffic Modelling1 Modelling very large Transport Systems Joan Serras Department of Design, Development, Environment and Materials The Open University

31st March 2009One-day Conference on Traffic Modelling2 Presentation outline  Introduction: a Multilevel Representation on transport systems  The TRANSIMS modelling system and its modules  A simulation of Milton Keynes using TRANSIMS  Conclusions and further work

31st March 2009One-day Conference on Traffic Modelling3 Introduction  The role of subsystems is essential on the behaviour of very large areas  Transport network models available which can address such areas (~10 6 inhabitants)  These models represent the road network at one level  TRANSIMS is not an exception  A methodology has been implemented to generate a multilevel representation using a simulation of Milton Keynes with TRANSIMS

31st March 2009One-day Conference on Traffic Modelling4 The TRANSIMS modelling system  Developed in Los Alamos during 1990s  Forecast the travel behaviour of a study area: information on traffic impact, congestion and pollution  Relevant studies: First study (1997): metropolitan region within Dallas (~200,000 travellers) Portland Study (2002): ~1.5 million travellers Swiss study (2004): morning peak simulation (~1 million trips) – 7.2 million inhabitants

31st March 2009One-day Conference on Traffic Modelling5 The TRANSIMS modelling system  Microscopic approach: travel demand estimated at the person level “synthetic population”: a virtual representation of all the individuals living in the study area Activity-based demand rather than trip-based  Urban activity locations defined at the household level  Output of the person movement on a second-by-second basis (24h simulation)  Parallel computing

31st March 2009One-day Conference on Traffic Modelling6 TRANSIMS’ core modules

31st March 2009One-day Conference on Traffic Modelling7 A simulation of Milton Keynes using TRANSIMS  Purpose of the study: Can we get the data to build a multilevel representation from the TRANSIMS output? Check its functionality in our system (cluster at the OU) Can we adapt it to simulate a non-US city? (synthetic population generation constraints) Significant output?  Constraints: Prime use of the software in UK lack of time (PhD period) Lack of resources: only me!  Due to constraints: many assumptions were done

31st March 2009One-day Conference on Traffic Modelling8 A simulation of Milton Keynes using TRANSIMS  Facts about Milton Keynes population (Census 2001): Population: ~200,000 inhabitants (urban area: ~170,000 inhabitants) Commuters (~60,000 commuters):  22,000 people commuting outside Milton Keynes (mainly to London area)  39,000 people commute to Milton Keynes  The Milton Keynes road network: A road grid (10 “horizontal” x 11 “vertical roads”) 1km 2 each grid for easy access between them ~300 roundabouts GIS representation: 2630 nodes and 3457 links

31st March 2009One-day Conference on Traffic Modelling9

31st March 2009One-day Conference on Traffic Modelling10 A simulation of Milton Keynes using TRANSIMS  Milton Keynes network From NTFS format to TRANSIMS format No traffic lights, no public transport  The synthetic population (Census 2001) US Census incompatibility: new method implemented  Household structure (150,000 inhabitants) Commuters (26,000 to MK; 13,000 out of MK)  Activity Generation survey from Balcksburg, VA (lack of time – not that different: work, shop, visit activity types kept)  Feedback 50 iterations between Router and Microsimulator

31st March 2009One-day Conference on Traffic Modelling11 A simulation of Milton Keynes using TRANSIMS  Clips on the Milton Keynes model can be seen in the following website:

31st March 2009One-day Conference on Traffic Modelling12 Conclusions and further work  A simulation of Milton Keynes using TRANSIMS has been produced at the OU  Fairly good results have been produced  Significant margin for improvement Currently working on improving the model  Data has already been used on a two-level representation More levels need to be defined in order to infer relevant conclusions