Comparing evaluations of PTV Vissim with evaluations according to HBS

Using the evaluation results obtained with Vissim, you can carry out an evaluation according to HBS (Handbuch für die Bemessung von Straßenverkehrsanlagen, Manual for Road Infrastructure Evaluation), a system of rules applied for economic construction of road infrastructure in Germany.

Thereby, a systematic deviation between the simulation results and the parameters analytically calculated according to HBS might occur:

• The HBS calculation is based on a model of traffic and nodes that is abstract to a certain degree. It cannot always include local particularities, as is possible with the detailed modeling of microscopic simulation in Vissim.
• The evaluation parameters of the HBS refer to a static and thus long-term case, e.g. to wait times. They analytically account for the wait time shares of all vehicles passing the node. During simulation, the recording is limited to the section for which modeled travel time measurements or delay measurements are available. In case of congestion according to HBS calculation, there is a much steeper increase in wait times than shown in the simulation with Vissim. Make sure you account for this when evaluating the results.

Note: Due to the stochastic nature of the simulation, random fluctuations occur in the results of the individual simulation runs. A more reliable assertion is only reached through averaging the results of a sufficient number of simulation runs with different random seeds.