Accident repeatability from one year to the next was found to be high at 60 intersections (r equals 0.64) and 170 spot locations (r equals 0.59). Nearly half of the 209 Kentucky locations designated as hazardous by accident criteria were found to have been so identified falsely because of random accident occurrences. Conflict counts were conducted at 5 intersections in central Kentucky to determine characteristics of conflict data. Good reliability was found between observers in simultaneous counts of conflicts and weaves with r values as high as 0.93. Traffic volumes accounted for only about 30 percent of the variation in numbers of conflicts. Reductions in conflicts and accidents that resulted from such safety improvements as installing left-turn signal phasing, raised pavement markers, and green-extension systems at numerous locations were determined. A revised procedure for collecting and utilizing conflict data was described. /Author/ This paper appeared in TRB Research Record No. 667 (1978), Highway Capacity, Measures of Effectiveness, and Flow Theory, p. 48-57.
Samenvatting