Modelling very large Transport Systems

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Modelling very large Transport Systems

• Joan Serras
• Department of Design, Development, Environment
  and Materials
• The Open University

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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

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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

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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

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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

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TRANSIMS core modules
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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

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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

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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

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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_simCl
  ips.htm

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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