EVALUATION OF THE EFFECTIVENESS OF CRASH CUSHION DELINEATION

The objective of this study was to evaluate the effectiveness of a limited number of crash cushion delineation techniques in the field. Three candidate treatments were selected for field testing: (a) a yellow diamond-shaped object marker, (b) a yellow-and-black chevron-patterned nose panel, and (c) yellow-and-black chevron-patterned nose and back panels. Because accidents involving crash cushions are relatively rare events, it is difficult to make statistically valid comparisons. In this study vehicle encroachments into the gore area were considered to be indicators of the potential for accidents with crash cushions. Studies were conducted at three sites in El Paso, Texas. A low-light-level camera and time-lapse video recorder were used to collect continuous encroachment and traffic volume data at the sites. Three candidate delineation treatments and the existing delineation treatment were tested at each of the study sites. A classification system was developed to differentiate among the gore sites on the basis of the geometrics of the gore approach. Data were collected over a 3-day period for each of the candidate treatments and for the existing treatment at the three sites. Crossover rates were used to compare the effectiveness of the delineation treatments. Analysis of the data indicated no difference in crossover rates among the treatments. The results, based on a limited sample, suggest that added delineation did not reduce crossover rates at locations where sight distance was not a critical factor and that accident problems at these sites may not be related to poor conspicuity alone, but instead may have also been influenced by informational deficiencies in signing and markings.