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” Queue length definitions The Austroads report discusses the use of queue length for model validation and states that "… the issues with both the queue calculation within traffic models and accurate on-site measurement is a common issue …". In relation to this, it is useful to discuss different queue length definitions that can be used in models, and the need for the field surveys to match the definition used in the model used...