Microsimulation and Analytical Methods for Modelling Urban Traffic

Abstract

Microsimulation models can help with the analysis of complex traffic problems in urban areas, alongside the analytical techniques that are in use. However, concerns are often expressed regarding misuse of microsimulation. This paper focuses on compatibility between microsimulation methods and established analytical techniques that are used in traffic engineering. Several key components of traffic models are discussed, and various recommendations are made, with a view to improving the practical usefulness of microsimulation models. These include (i) the use of simulation for capacity analysis, (ii) modelling of queue discharge (saturation) flow rate, queue discharge speed and other queue discharge parameters at signalised intersections, and relating them to the general queuing, acceleration and car-following models used in microsimulation; (iii) modelling of gap-acceptance situations at all types of traffic facilities, and (iv) estimation of lane flows at intersection approaches, and relating this to lane changing models used in microsimulation. The consistency of definitions and measurement methods for traffic performance variables such as delay (stopped, geometric, etc) and queue length (cycle average and back of queue) is also discussed. It is suggested that comparison of specific microsimulation and analytical model components is useful towards model benchmarking for evaluation of new and existing models. Towards this end, a simple signalised intersection case is specified in sufficient detail to enable assessment of two basic traffic model components, namely queue discharge flow rate and lane flow distribution.