Freeway Ramp Merging Process Observed in Congested Traffic: Lag Vehicle Acceleration Model

This paper is the second of a pair of papers that discuss the modeling of freeway ramp merging behavior under congested traffic conditions. The fist paper focused on the modeling of the merged vehicle (from the ramp) and was presented in the 15th ISTT, while this paper develops a model for the lag vehicle (approaching the ramp area from the freeway) in order to provide a complete picture of driver interaction behaviors at the time of merging. A four year extensive study that has been undertaken to investigate traffic behavior and characteristics during the traffic merging processes under congested traffic flow in order to design a safer and less congested merging points. The acceleration and merging process from an entrance ramp to freeway lanes constitutes an important aspect of freeway traffic operations and ramp junction geometric design. Competing traffic demands for space influence this process regarding both the ramp freeway junction and the upstream freeway lanes. A merging driver must make a series of decisions and carry out control tasks, all within the driver capability to process the roadway and traffic information and interpret it into speed and position control responses. This paper presents a methodology for collecting field data, analyzing freeway merging behavior data and developing a freeway lag vehicle acceleration model.