EFFECT OF INTERSECTION CONGESTION ON ACCIDENT RATES

Although there is general agreement that accident rates are highest during the periods of the day when traffic volumes are low, the change in accident rates as facilities become more congested is poorly understood. The peak-hour accident rates at several hundred signalized intersections in Albuquerque were examined in relation to their level of congestion, as reflected by volume/capacity (v/c) ratios. Accident rates exhibited a small but significant positive correlation with the amount of entering traffic. On average, intersection accident rates are at a minimum in the range 0.6 less than or equal to v/c less than or equal to 0.8. However, equations developed for estimating accident rates as a function of v/c had such high standard errors that they could not be used for predictive purposes.