OPTIMUM AXLE-LOAD LIMITS IN OMAN

The cost of highway maintenance and construction increases as the axle loading increases, whereas the cost of cargo transport decreases as axle loading increases because fewer trips are needed to transport a given amount of cargo. Each country has its own specific optimum axle-load limit that produces the lowest total cost in highway maintenance and construction and in cargo transport. An analysis was performed, for a developing country, wherein existing axle-load distribution patterns under various axle-load limit alternatives. Subsequent changes in traffic volumes were also estimated. Pavement maintenance and construction requirements were estimated on the basis of total equivalent number of standard axles, for which costs of combined total and relative levels were examined. Some conclusions are (a) that for a given highway the optimum limit exists only for a range of intermediate traffic levels (for the low and high traffic levels, no-limit case always yields the least total cost), (b) the although the total cost may not vary significantly by axle-load limits, public and private sectors share the total cost in considerably different proportion under different axle-load limits, and (c) that an axle-load limit may have significantly different effects on different types of vehicles. (Author)