Doctoral Dissertations

Date of Award

3-1988

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

K. W. Heathington

Committee Members

William L Grecco, Jack B. Humphreys, Richard D. Sanders, Fredrick J. Wegmann

Abstract

Research to improve safety at railroad-highway grade crossings has been ongoing for some fifty years; however, the methods used for warning motorists of impending danger at the crossing have changed little during this time. This research evaluated several innovative active warning devices in both the laboratory and the field, and documented their performance under normal conditions at existing crossings. The three basic systems being evaluated were four-quadrant gates, four-quadrant flashing light signals, and highway traffic signals.

In the laboratory study, 32 test subjects, two questionnaires, and an instrumented vehicle were used to evaluate the perceived and operational performance of two alternatives for each of the three basic systems in a near real-world environment. Each of the six innovative devices (two alternatives for each of three systems) tested were perceived as superior to existing active warning devices with the fourquadrant gates being the most effective and the four-quadrant flashing light signals the least effective of the three systems. In terms of driver behavior, the four-quadrant gates were the best performing for all measures of effectiveness with the ranking of the other two systems varying depending on the measure being evaluated. Based upon these results, one alternative of each basic system was chosen for a subsequent field evaluation.

In the field study, an automatically controlled video data collection system was used to collect driver behavior data at three grade crossings in Knoxville, both before and after the new devices were installed. Each of the innovative devices performed acceptably, both from a technical and practical standpoint. Two of the devices, the four-quadrant gates and highway traffic signal, would improve safety at railroad-highway grade crossings. The third device evaluated in this research, four-quadrant flashing lights, resulted in no measurable differences in driver behavior. Based upon these results, it is recommended that four-quadrant gates and highway traffic signals be tested at additional crossings, and if these results are also favorable, that an effort be made to have them adopted by the Manual on Uniform Traffic Control Devices as standard active warning devices for use at railroad-highway grade crossings.

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