Study on the Equivalent Travel Time Cost of Road Ride Quality Deterioration

摘要

As one important kind of road user cost, the travel time delay caused by the deterioration of road pavement conditions has been under-reported in the previous studies. In reality, drivers need to adjust their vehicle speeds to achieve the same ride comfort level if the pavement surface is getting worse. In this paper, the RQI (ride quality index) is selected as the measure of ride comfort. The equivalent travel time cost of the RQI difference of two roads at the same speed level, which could be viewed as the equivalent travel time cost of the RQI deterioration for one road, is defined as the travel time difference under the same RQI level of the two roads. Using IRI (international roughness index) as a bridge between RQI and speed, the relations between RQI and speed are extracted firstly. Then, RQI values under different speeds for fifty selected typical road surfaces are calculated, respectively. Following that, the difference of RQI values at the same speed level of 80 km/h and the difference of speeds at the same RQI level for any two of fifty roads are calculated. Good correlations are found between them. Using this relationship, the equivalent travel time costs of RQI deterioration is explored. The results show that the equivalent travel time cost will increase with deterioration of RQI increasing. The equivalent travel time cost caused by the RQI deterioration could be more than 20 percent of the total travel time cost and should not be ignored in practical applications.