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A critical review of Austroads Report AP-R621-20
Revised version published as Austroads Report AP-R647-21 “Management of Traffic Modelling Processes and Applications”
Summary for Second Edition
A detailed critique report entitled Transport modelling for project managers - critique of AUSTROADS Report AP-R621-20 was published in August 2020. In response to the critique report, Austroads carried out a major revision of Report AP-R621-20 and replaced it with Research Report AP-R647-21 (Management of Traffic Modelling Processes and Applications). A second edition of the critique report titled Management of traffic modelling - A critique of Austroads Report AP-R621-20 (Transport modelling for project managers), 2nd Edition was prepared.
Both the first and second editions of the critique report should be of interest to transport and traffic modelling project managers, guide developers and software users.
Transport and Traffic Model Categories
A transport and traffic model categorisation system is proposed. This uses the geographic extent of the area to be modelled and the purpose of the model use as the basis of Model Types with clear relationships to the Model Level of Detail and Modelling Technique.
Assessing Software Packages
Most software packages have capabilities for modelling intersections and networks, use a mixture of analytical and simulation modelling techniques, and involve macroscopic, mesoscopic and microscopic levels of detail.
Capacity: Model Estimation of Key Parameters
Estimation and calibration of key capacity parameters saturation flow, follow-up headway and critical gap as a function of road geometry, traffic flows and signal timings should be enforced for microsimulation and mesosimulation models as used in analytical models.
Peak Demand (Analysis) Period
While analytical models are capable of modelling congestion affects with the analysis of a single peak flow period, microsimulation using individual vehicles needs to use multiple flow period modelling.
Pedestrians and Vehicle Classes
The modelling of public transport, bicycles and pedestrians is an essential part of analytical intersection and network models.
Queue Length for Model Calibration
In using queue length for model validation, different definitions (back of queue, queue at the start of green period, cycle-average queue as well as their average and percentile values) should be clearly understood.