A microscopic simulation model of merging operation at motorway on-ramps

This thesis presents the development and application of a microscopic simulation model of merging operation at motorway on-ramps. At the core of the simulation model are several behavioural models of driver-vehicle system; each is capable of mimicking one of driving sub-tasks such as merging, car following etc. The simulation of merging operation is achieved through programming many driver-vehicle systems to interact according to the behavioural models within a simulated network. Two behavioural models developed and validated in this research are the model of car following behaviour and the model of merging behaviour. Time-series data of merging manoeuvres and related motorway driving has been derived from the time-space trajectories of interacting vehicles. These have been based on detailed data collected in a large-scale, long-term observation using a combination of camera technology and the TRG instrumented vehicle. Data reduction and processing techniques have been developed and the accuracy of the data is discussed. In this research, the fundamental understanding of merging behaviour has been improved by examining the merging process using accurate time-series data and incorporating driver’s eye-movement analysis. The merging behaviour analysis has been extended to cover slip road upstream of the merge and passing vehicles on the shoulder lane of the motorway. The merging behaviour was analysed based on data on gap leaders, merging vehicles and gap followers, covering dynamic control behaviour of following gaps and gap acceptance behaviour etc. The model of merging behaviour achieved by treating two interacting traffic streams, the merging and passing traffic as an entity, shows a satisfactory performance. The model of car following behaviour has been developed based on an extensive investigation of possible model formulations using a data-driven approach. Detailed results from the model calibration and validation process are presented. The behavioural models have been implemented in a computer simulation program, and has been applied to evaluate the impacts of ramp metering on traffic operations. Results indicate that the simulation model reproduces realistic merging operations and can be used as a stand-alone simulation program for merging related applications. Alternatively, it could be implemented as a module in a network-wide traffic simulation model to replace the existing merging logic.