Citation

Renshaw DL, Carter EC. Transp. Res. Rec. 1980; 753.

Copyright

(Copyright © 1980, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

One objective of the Baltimore County road-rating project was to identify problem sections of county-maintained roadway. A safety rating was determined for each roadway section in the county inventory; sections vary in length and average daily traffic (ADT) as well as in physical and environmental aspects. Two problems in rating roadway sections are the determination of an adequate number of years of accident data and the choice of clear measures of hazardousness. Short sections that have low ADT often produce rates that indicate high hazard, but with low certainty that they are high-hazard sections; however, the use of a longer sample period may involve many changes in the roadway's physical characteristics, which may invalidate results. The study team attempted to determine which roadway sections were most hazardous and represented the most critical needs. The relationship of the exposure available for analysis on each roadway section, the required exposure for the level of analysis, and the years of accident data required were studied and summarized in a nomograph. A three-year accident data sample was selected by using this nomograph. High-hazard sections were first identified with accident-number and accident-rate measures, and then they were ranked. More sophisticated measures were used to rate and rank sections for hazardousness, and all rankings were compared. Finally all sections were reevaluated, and those that were hazardous with a high level of certainty were identified.