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Modelling very large Transport Systems

Modelling very large Transport Systems. Joan Serras Department of Design, Development, Environment and Materials The Open University. Presentation outline. Introduction: a Multilevel Representation on transport systems The TRANSIMS modelling system and its modules

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Modelling very large Transport Systems

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  1. Modelling very large Transport Systems Joan Serras Department of Design, Development, Environment and Materials The Open University One-day Conference on Traffic Modelling

  2. 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 One-day Conference on Traffic Modelling

  3. Introduction • The role of subsystems is essential on the behaviour of very large areas • Transport network models available which can address such areas (~106 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 One-day Conference on Traffic Modelling

  4. 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 One-day Conference on Traffic Modelling

  5. 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 One-day Conference on Traffic Modelling

  6. TRANSIMS’ core modules One-day Conference on Traffic Modelling

  7. 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 One-day Conference on Traffic Modelling

  8. 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”) • 1km2 each grid for easy access between them • ~300 roundabouts • GIS representation: 2630 nodes and 3457 links One-day Conference on Traffic Modelling

  9. One-day Conference on Traffic Modelling

  10. 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 One-day Conference on Traffic Modelling

  11. A simulation of Milton Keynes using TRANSIMS • Clips on the Milton Keynes model can be seen in the following website: • http://design.open.ac.uk/serras/miltonKeynes_simClips.htm One-day Conference on Traffic Modelling

  12. 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 One-day Conference on Traffic Modelling

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