There are several standard models of vehicle operating costs (vocs) that are advocated for the appraisal of rural road investment indeveloping countries. The world bank's highway design and maintenance standards model (hdm) and the transport and road research laboratory's road transport investment model (rtim) incorporate different models of vocs based on research carried out in kenya, the caribbean, brazil, and india. In the hdm, the user can select the most appropriate voc model to suit local conditions. Because the different models give different estimates of benefits, a convenient way of selecting the most appropriate model form and of calibrating the results is needed. The role of competitively determined freight tariffs to assist with this task was investigated using data from rough and smooth roads in pakistan. Although there are particular problems with usingfreight rates such as seasonality, empty running, and traffic directional flow imbalance, the results show that freight rates could prove to be useful in checking models of vocs. Vehicle maintenance costs in pakistan are particularly low, and therefore all of the standard models overestimated the difference in operating costs (per vehicle-kilometer) between rough and smooth roads. However, vehicle load weights were found to be lower on rough roads than on smooth roads. If loads increased with road improvement, important additional benefits would result that could be easily overlooked. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 1.
Abstract