Capacity and level of service by simulation – A case study of TRAF-NETSIM

We explore the prospect of using TRAF-NETSIM, a microscopic simulation model, to estimate capacity and level of service through a case study. In the case study, we collected stopped delay, saturation flow, bus dwell time, double parking duration, vehicle and pedestrian volumes, etc. These data served as the bases to run and to calibrate the model, and to check the model results. Although TRAF-NETSIM does not provide capacity and level of service directly, we showed how to make use of its detail simulation capabilities and graphics to obtain capacity and level of service. We also showed how to calibrate the model to represent local traffic conditions. The simulated capacity, stopped delay and level of service were very close to the field results. Since TRAF-NETSIM is a stochastic model, there is concern that its results may vary. We examined its variability by inputting different random number seeds with different simulation times. We find that the variation of capacity was insignificant while that of stopped delay was mixed. We also examined the required number of runs and length of simulation times to obtain 95% level of confidence. TRAF-NETSIM has many advantages. Its animated and static graphics can show what is going on or how the result is derived. Its numerous calibrating parameters enable it to be applicable to many traffic conditions. It produces many statistics which are useful for other analyses. It considers individual factors as well as the interaction of different factors which may affect capacity and level of service. One can analyze the impacts of these factors on one intersection or on the network as a whole. The prospect of using a simulation model such as TRAF-NETSIM for capacity and level of service appears to be promising.