Doctoral Dissertations

Date of Award

12-1989

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

Kenneth W. Heathington

Committee Members

William L. Grecco, Jack B. Humphreys, Frederick J. Wegmann

Abstract

As of 1987, over 54,000 of the nation's 192,454 railroad-highway crossings were equipped with active traffic control devices, i.e., flashing light signals with or without automatic gates. Although these active devices have enhanced crossing safety, there is evidence that they are not performing as intended. Research indicates that serious safety problems result when drivers intentionally elect to drive around or through functioning active devices. In fact, over one-half of all grade crossing fatalities occur at crossings with active traffic control even though these crossings account for less than 30 percent of the total crossings. One out of ten grade crossing accidents involves a vehicle driving around a lowered gate arm.

The purpose of this research was to: (1) determine the extent and nature of undesirable driver actions at grade crossings with active traffic control; and (2) identify driver-related factors which influence this undesirable driver behavior. A multi-faceted research approach was used. Field studies were conducted at three grade crossings. The results of these studies documented the extent of undesirable driver actions at typical active crossings, and they provided data for an in-depth assessment of the effects of warning time on driver behavior. A laboratory study was conducted to further evaluate drivers' expectancies and tolerances with respect to warning times.

To identify driver-related factors which, together with warning time, influence driver crossing behavior, a driver survey was developed and administered nationwide to 562 drivers. In the survey, drivers reported their comprehension of the active devices and pertinent traffic laws, recognition of the grade crossing hazard, tendencies for risk-taking, respect for active crossing devices, exposure to active systems, and general demographic characteristics. The effects of these driver-related factors on the drivers' self-reported behavior were then evaluated using multivariate analysis of variance (MANOVA) and discriminant analysis techniques.

The results of the research indicate that undesirable driver behavior at active crossings is a wide-spread problem. (Undesirable driver behavior refers to drivers intentionally going around or through functioning active traffic control devices.) Such behavior has a very negative effect on overall crossing safety.

Several factors were found to significantly influence driver behavior at active crossings. They include: (1) the driver's perception of the crossing hazard; (2) the driver's comprehension of his/her duties; (3) the driver's perceptions regarding system reliability; and (4) the driver's age, gender, and driving experience. Drivers who "normally" engage in undesirable behavior tend not to accept that their actions are hazardous, and they believe that their actions are legal. Also, they have been exposed to false activations and believe that false activations are common. They typically are male, relatively young, and frequent drivers.

The length of the warning period also has a significant influence on driver behavior at active crossings. Warning times between 20 and 35 seconds minimize the number of undesirable driver actions at crossings with flashing light signals and at gated crossings. Warning times in excess of 40 seconds at crossing with flashing signals, and in excess of 60 seconds at gated crossings, erode drivers' credibility in the active warning, and greatly increase the number of undesirable driver actions. Excessive warning times also promote aggressive and very risky crossing behavior.

Based on the research findings, recommendations are presented for mitigating undesirable driver actions at grade crossings with active traffic control. These include recommendations for minimum, maximum, and desirable warning times. General recommendations are also presented relative to the major driver factors which influence undesirable driver behavior at active crossings.

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