Development of simulation model for assessing the performance of weaving sections on interchanges

Abstract

Weaving section is a common feature of an urban highway. A weaving area is characterized by frequent lane-changing maneuvers, which will reduce the capacity of a dual carriageway road. It is formed when a merge area is closely followed by diverge area, or when an on-ramp is closely followed by an off-ramp and the two are joined by an auxiliary lane. Current procedures and existing simulation models are inadequate for a detailed assessment and evaluation of traffic behaviour on the merging and diverging area. There is a need to develop an appropriate tool to assess the merging and diverging area accurately because such an assessment involves a large number of variables. This study aims at developing a simulation model of traffic operations at weaving sections in Malaysia based on some variables which affect weaving section performance. The microscopic time scanning simulation model developed is capable of representing and investigating traffic operations in merging areas. The model, which is written in the FORTRAN programming language, was validated and calibrated using data collected at three locations of weaving area in Kuala Lumpur. The lengths of the weaving areas considered were site1=450 m, site2=575 m and site3= 350 m, respectively. The simulation model was used to evaluate the capacity of Type A weave area with a range of traffic flow conditions. The regression model described in this thesis is based on the mainline volume, freeway to ramp volume and ramp to freeway volume. The comparison between on-ramp field data and relevant simulation results showed less than 8% disparity. The simulation results showed that for a weaving length less than 200 m the interactions between vehicles increase significantly and the capacity decrease considerably.