Development of a Microsimulation Program to Study Freeway Ramp Merging Process in Congested Traffic Conditions

This work describes a micro simulation program that is developed to study freeway ramp merging phenomena under congested traffic conditions. First, the results of extensive macroscopic and microscopic studies are used to establish a model for the behaviour of merging drivers. A theoretical framework for modeling the ramp and freeway lag driver acceleration-deceleration behaviour is then presented. This methodology uses the stimuliresponse psychophysical concept as a fundamental rule, and is formulated as a modified form of the conventional car-following models. Data collected at the two merging points of the Tokyo Metropolitan Expressway are used to calibrate the hypothesized ramp and freeway lag vehicle acceleration models. Next, based on this behavioural model, the Freeway Merging Capacity Simulation Program (FMCSP) is developed to simulate the actual traffic conditions. This model evaluates the capacity of a merging section for a given geometric design and flow condition. The validation of FMCSP performed at microscopic and macroscopic levels using the observed flow, vehicles trajectories, and lane changing maneuver. The developed FMCSP is applied to investigate the lane changing restriction strategy as well as the study of ramp driver behaviour by establishing a link to a driving simulator. The results indicated that the FMCSP is capable of simulating the actual traffic conditions of congested freeway ramp merging sections to study the complex ramp merging phenomena.