Citation

Bunker JM, Haldane MJ. Road Transp. Res. 2003; 12(3): 3-15.

Affiliation

School of Civil Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia

Copyright

(Copyright © 2003, Australian Road Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Multi-combination vehicles (MCVs) thatrequirelong times to clear intersections or railway level crossings from rest can cause excessive delay to other traffic, and compromise safety if sight distances are inadequate. Intersection clearance time is of most concern in urban areas, because of its effect on vehicle productivity and the safety and efficiency of intersections. Clearance time at railway level crossings is of concern because trains require clear passage. Over a given merging distance, an MCV attains a lower speed than smaller vehicles, which may compromise the safety and efficiency of the merge area. This paper reviews current specifications for clearance time and acceleration and speed characteristics of MCVs. It reports an in-field testing program conducted to measure trajectories of a range of MCVs and a model calibrated from the tests to describe vehicle trajectory. It then examines trajectories of MCVs based on the model, compares results with current specifications, and identifies avenues of future research. An understanding has been gained from this model on the retarding influences of mass and grade on acceleration capability and attained speed. Curves estimating clearance times for crossing widths, and speed as a function of travel distance, have been established for each MCV tested, across a range of grades. The model has been used to quantify acceleration capabilities of various MCVs. It is recognised that further calibration of the trajectory model is required for estimation of trajectories over longer distances and higher speeds, and for prime movers of varying power and gearing.

Language: en