Overview
Transportation models use volume delay functions, especially for assigning traffic to the network. For major roads in urban areas, such volume delay functions are missing. This is a serious lack, particularly for the modelling of urban traffic. This research project help to solve this problem. Extensive traffic surveys on the relationships between delays and volumes on typical urban roads provide the data needed to set up micro simulation models for the simulation of typical constellations in urban areas. For the simulation runs typical patterns of effects disturbing traffic flows, such as pedestrian crossings, bus stops, etc. are assumed.
The goal of the research project is the derivation of practice-suited volume delay functions (dependence of travelling speeds on traffic volume) for sections of major urban roads outside areas influenced by junctions. The volume delay functions are deduced from the results of micro simulation runs. They are calibrated and validated using empirical data.
There are the following steps provided:
- Literature study
- Coordination with SVI 2001/057
- Typing of road / environment constellations
- Choice of case studies
- Empirical studies / evaluations
- Leaving the node areas of influence
- Traffic flow microsimulation
- Derivation of resistance functions
- Instructions for use
- Research Report
Funding
Results
The results of the simulation runs serve to deduce volume delay functions for typical urban road segments. Finally, mathematical functions appropriate for use in transport models are defined. The research results can immediately be implemented in practical transport modelling and they improve model results substantially.
The research results flow directly into the practice of traffic modeling in urban areas. They significantly improve the reliability of the model results.
The study makes recommendations regarding the practical use of the BPR-function in the context of transportation modeling and provides guidance for the choice of the appropriate traffic situation and level of free flow speed. It also shows the possibility to group traffic situations as a means to facilitate the task of network coding.
For the first time, the study provides parameters of the BPR-function for typical urban road sections in Switzerland based on empirical evidence. As such, the study contributes to the improvement of transportation modeling in the Swiss urban context.