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

31st March 2009 One-day Conference on Traffic Modelling 1

Modelling very large Transport

Systems

Joan SerrasDepartment 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 A simulation of Milton Keynes using

TRANSIMS Conclusions and further work


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


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


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


TRANSIMS’ core modules


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


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




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



Clips on the Milton Keynes model can be seen in the following website: http://design.open.ac.uk/serras/miltonKeynes_simClips.htm


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

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

Documents

transims slide

day conference

simulation of milton

transims milton keynes

traffic modelling9 slide

level transims

transims output

transims format