AITPM presentation

1. Application of Aimsun Hybrid Model in
Transport Planning
Bill Chen & Graeme Inglis

2. Agenda
1. Project background – Wilton Junction Precinct
2. Road network
3. Transport Management and Accessibility Plan
4. Strategic modelling
5. Mesoscopic modelling
6. Hybrid modelling
7. Discussion
8. Conclusion
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3.  Part of the Potential Housing Opportunities Program
 Currently Wilton is a small village (1,890 people and 590
homes)
 A new town is planned in Wilton Junction Precinct
 Residential (about 12,000 dwellings)
 Employment (11,000 jobs)
 Retail (at a new town centre)
 School and other facilities.
http://www.planning.nsw.gov.au/wiltonjunction
Project background – Wilton Junction Precinct
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4.  Hume Highway
 Interstate highway linking Sydney and Melboune
 Main north-south corridor accessing Wilton
 Two lanes in each direction and speed of 110 km
 B-double route
 Picton Road
 State road travelling between Picton and Mount
Ousley Road
 Main west-east corridor accessing Wilton
 one lanes in each direction
 freight route to Port Kembla and a commuter traffic
route on weekdays
 Other key roads including Remembrance Drive and
Appin Road/Wilton Road
Road network
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5. Transport management and accessibility plan
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 TMAP
 Support the application for the rezoning of Wilton
Junction Precinct
 Travel requirements of the Precinct by road, public
transport, walking and cycling
 3-Tier Transport modelling
 identify the transport impacts of the Wilton Junction
Precinct
 assess the provision and staging of the required
traffic and transport infrastructureone lanes in each
direction
 Macro/Meso/Micro

6. Strategic modelling
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 Sydney Strategic Travel Model (STM)
 Maintained by BTS and Sydney GMA
 provide origin-destination (OD) demand and
patterns for the existing year
 determine the future year trip generation, trip
distribution and mode split for development
 Subarea matrices were extracted from STM for
study area to consider impact on wider regional
network

7. Mesoscopic modelling
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 Select modelling platform
 Relatively recent development and has been gaining
popularity in NSW
 Intermediate level of detail between Macroscopic
and Microsimulation
 Quickly assign traffic to alternative routes at wider
regional area
 Test initial intersection design option for the
development area with acceptable level of accuracy
 AIMSUN software was selected
 Model network development
 Cover Bargo to Campbelltown (about 35 km in
distance) and Picton to the Illawarra Escarpment
(about 36 km in distance)
 Zone aggregation and disaggreation

8. Mesoscopic modelling
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 OD demand estimation
 Initial cordon subarea matrices extracted from STM
 Restructure matrices to fit Meso zone system
 Furness matrix estimation
 Adjust matrices with static traffic assignment
 Fine-tune at dynamic traffic assignment
 Traffic assignment
 Considering the rural environment of the study area,
stochastic dynamic assignment method
 Traffic proportionally assigned to alternative travel
routes with preference over shortest routes

9. Mesoscopic modelling
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 Calibration and validation
 Network coding
 Routing
 Traffic flows
 Travel time
 Model stability
 Existing road conditions
 Heavy congestion on Narellan Road
 Long delays for the turning traffic at the Hume
Highway/Picton Road intersection
 Heavy but moving flows along Hume Highway and
Picton Road

10. Hybrid modelling
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 Micro pocket created for Wilton Junction Precint
 Wider road network modelled at Meso level
 Model network, zone system and database
common to both level
 Parameters only applied to Micro level were
calibrated
 Detailed analysis of intersection design at Micro
level
 Transport infrastructure requirement and staging
plan were determined with Hybrid model results

11. Discussion
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 Global parameter in AIMSUN Meso
 Time reaction is most influencing parameter
 Difficult to calibrate it for the existing condition
 TSS research indicated lower value leads to aggressive and unrealistic
driver behaviour
 SIDRA model was used to cross check Meso model results
 Our model review experience showed this parameter was commonly
changed to make model calibration results look right and no appropriate
justification was provided
Intersection Meso SIDRA
Picton Road/Pembroke
Parade
LOS B LOS C
Picton Road/Almond Street LOS B LOSC

12. Discussion
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 Sensitivity test for different traffic assignment method
 Model was reviewed by RMS and found to be fit for purpose
 Dynamic User Equilibrium (DUE) was suggested to test to check robustness of
model
 Base model was recalibrated and validated using DUE to conduct like with like
comparison for future year scenario
 DUE tended to assign more traffic to route with higher hierarchy and speed
 Propose infrastructure upgrades would be able to accommodate the increased
demand on key routes
 Confidence in our proposed infrastructure requirement was enhanced.

13. Conclusion
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 First application of Hybrid modelling for large-scale development in NSW
 3-tier modelling framework is suitable for capturing development impact in wider regional
context and local envrionment
 AIMSUN Mesoscopic modelling is able to quickly assess route choice in large network and
test initial intersection design with acceptable level of detail
 Microsimulation pocket can be created to conduct detailed analysis of core study area
 Road network, zone system and database are common to both Meso and Micro areas of
network can avoid manual interfacing between different Meso and Micro software packages
 Time reaction is one of the most influencing parameters in AIMSUN Meso. Caution should
be taken when calibrating parameter value. Low parameter value tends to underestimate
traffic delays
 Sensitivity test for DUE and DTA can be useful to build confidence in model robustness and
proposed upgrade scheme