Over the course of two winter seasons, the New Hampshire Department of Transportation collected data on pavement marking retroreflectivity, snowplow activity, and traffic volumes at twelve sites around the state to assessthe retroreflective performance of the state's pavement markings in anticipation of future rulemaking on minimum levels of retroreflectivity for markings. All twelve sites were two-way, two-lane highways. At each site, they attempted to collect retroreflectivity data in the fall and spring and the number of times each line was hit by a snowplow. Each site was near a permanent count station, so winter traffic volume data was also available. Out of a possible 96 lines that could have been used for analysis, missing data limited the number of lines available for analysis to 64. Theaverage retroreflectivity of the 64 lines in fall was 261 mcd/m2/lux (forboth colors). The average retroreflectivity reading for the spring values was 92 mcd/m2/lux. There was an average of 242 plow hits on each line and the average winter average daily traffic (ADT) at each site was 7,734.The authors created a cumulative distribution of the retroreflectivity values that indicate that 13 percent of the white markings and 20 percent ofthe yellow markings would have retroreflectivity levels below 40 mcd/m2/lux, which is the minimum level recommended in an Federal Highway Administration (FHWA) sponsored research effort. The authors also performed regression analysis of the retroreflectivity data as a function of the snowplow hits and passing traffic volume. None of the regression relationships identified a significant relationship between the factors.
Samenvatting