sydney-city-centre-review-of-environmental-factors

Traffic modelling and monitoring data
The network performance benefits and impacts of the proposal were assessed using
two traffic models as follows:
The Roads and Maritime network traffic model (AIMSUN) was used initially to
provide a high-level indication of congested areas and to identify the 17 work
site locations taken forward for improvement under this proposal (refer to
Chapter 2)
Intersection traffic modelling (using SIDRA) and first-principle assumptions
were then used to develop and refine traffic forecasts within each work site.
This approach was also used to assess localised intersection and corridor
performance and to develop traffic capacity improvements solutions for the
proposal (refer to Chapter 2).
Unlike a network modelling tool like AIMSUN, the SIDRA modelling undertaken
assumes unconstrained traffic conditions on the approaches to and exit from
intersections. This approach was used to develop a like-for-like comparison of
existing and post-construction operations. This comparison uses a consistent set of
inputs and assumptions and therefore directly indicates the capacity and consequent
performance benefits on an intersection by intersection basis. It is proposed that the
AIMSUN traffic model will be subsequently used as part of an ongoing process to
understand the overall network operation and estimate cumulative network benefits
of the proposal and other projects across the city centre.
Model inputs
The following information was used to develop, calibrate and validate both models:
Road network layout plans (eg lane configuration, vehicle/turn restrictions)
Bus infrastructure and operations
Kerbside uses (eg bus operations, taxi operations, parking, loading)
Classified mid-block vehicle surveys
Classified intersection turn counts
Intersection approach queue length surveys
Traffic signal phasing and timing data
Observed traffic conditions (eg driver behaviour, lane utilisation, pedestrian
behaviour).
Model outputs
Table 6-1 summarises the scenarios considered and modelled in the traffic and
transport specialist study.
Table 6-1
Traffic modelling scenarios and outputs
Modelling
scenario
Do nothing
Do
something
Network description and modelled outputs
Assessment of changes to traffic conditions and network
performance between 2014 and 2024 due to the
inclusion of the other committed transport project but not
the proposal.
Assessment of changes to traffic conditions and network
performance across the study area due to the inclusion
of the other committed transport projects and the
proposal.
Modelled year
2014 -
- 2024
Sydney City Centre Capacity Improvement 168
Review of Environmental Factors