It is demonstrated that travel time offers a sound measure of the level of urban traffic service and can be a basic criterion for a major street improvement priority formula. The overall level of service as obtained by peak-hour travel time studies in phoenix, arizona in 1947, 1957 and 1962 are compared. This comparison also related the level of service to population growth, increase in vehicle registration, city size and traffic volumes. Selected route segments are compared for change in average speed, vehicle delay and average daily traffic. In making these comparisons, street improvements that increased capacity are are identified. Examples of these improvements are street widening, intersection widening and provision of left-turn lanes, channelization, and removal of parking. The test formula used assigns major emphasis to delay rate, but also consideres collisions, traffic volume and structural condition of the pavement. The formula was evaluated by comparing the relative priority rating for selected major arterial street segments, as determined by the formula, to judgment rating of individuals. This improvement priority formula is not intended to replace judgement, but could be used as an aid to develop recommended capital improvement priorities for major arterial construction programs. Travel time was felt to be an effective measure of level of service both for individual routes and for urban street and freeway systems.
Abstract