Effects of Connector pattern on Traffic Assignment Results;Case Study: Qazvin

In Transportation Literature, in order to relate supply (street network) and demand (Traffic Zone) definition of centroid and its connector(s) is essential. Centroid and its connector(s) selection, despite its importance, are usually done based on the general knowledge of researcher from network, his/her judgment and experiment. The main purpose of this paper is to investigate the effect of centroid connection pattern on static traffic assignment. Using User Equilibrium approach, different scenarios of connections from one connector to all the possible connectors got evaluated. This issue is investigated in Qazvin network which has 113 traffic zones and approximately 400 thousands inhabitants. Applying 6 different scenarios showed that amending in pattern and number of connectors would result 10 percent change in average link volumes and about 20 percent change in total vehicle-kilometer of network. As a result of connection pattern and assessor multiplicity, it is difficult to specify the optimum pattern; this difficulty indicates the effects of connector pattern on traffic assignment results.