Citation

Zador P, Stein HS, Wright P, Hall J. Transp. Res. Rec. 1987; 1114: 1-10.

Copyright

(Copyright © 1987, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Previous research has shown that in single-vehicle crashes drivers tend to run off the road in the direction opposite the curve; that is, they miss the curve. Examined in this study are the short- and long-term effects of commonly used curve delineation treatments on the speed and placement of vehicles traveling on curves on rural two-lane highways in Georgia (46 sites) and New Mexico (5 sites). Vehicle speed and placement distributions at sites modified with the addition of chevrons, post-mounted delineators, and raised pavement markers and unmodified control sites were compared in terms of 10th percentile, 90th percentile, mean values, and standard deviations before and after modification. The modifications tended to shift the nighttime speed distributions upward, with an average speed increase of 1 to 3 ft/sec; however, in Georgia, chevrons had little effect on speed. Overall, when chevron signs were used at night, vehicles moved away from the centerline; they moved farther away when raised pavement markers were used. In contrast, when post-mounted delinetors were used, vehicles moved toward the centerline. Vehicle speed and placement variability were also slightly reduced with the use of chevrons and raised pavement markers. There was little change in the typical driver curve-following behaviors of corner cutting on curve lengthening. Few of the changes varied systemically by curve alignment or grade, and there was little evidence that short-term changes eroded over time. Although drivers did change their behvaior in response to the delineation modifications, there was no clear evidence that any one of the devices is superior to the others. The primary benefit of clearly delineating curves may simply be that it helps drivers better recognize that they are approaching a curve.

Record URL:
http://onlinepubs.trb.org/Onlinepubs/trr/1987/1114/1114-001a.pdf


TRT Terms: Before and after studies; Behavior; Drivers; Highway curves; Highway delineators; Lateral placement; Measures of effectiveness; Motor vehicles; Raised road markings; Ran off road crashes; Rural highways; Signs; Single vehicle crashes; Speed; Traffic speed; Two lane highways
Uncontrolled Terms: Effectiveness; Post-mounted delineators
Old TRIS Terms: Chevron signs; Raised traffic markings
Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control;

Language: en

Keywords

TRAFFIC SIGNS, SIGNALS AND MARKINGS; HUMAN ENGINEERING - Behavioral Research; AUTOMOBILE DRIVERS - Accidents