Trucks are used as the main mean of transporting goods in Thailand. Their hauling weights especially agricultural products and building materials usually exceed weight regulation specified by laws causing damages to the road surface pavement especially asphaltic concrete type of pavement which is the predominant type of pavements in Thailand and shorten the time interval to the next surfacing. This costs the government a huge sum of money in repairing roads and in many occasions, are used as a political issue. This thesis studies the impact of changing weight limits of the trucks. Five scenarios were looked at, the first one was being the prevailing condition where the hauling weight exceeded the limit (21 tons for 10 wheelers). Teh second dealt with the strict enforcement of the regulation and the remainders 3, 4 and 5 were about the increasing weight limits to 25, 30 and 35 tons respectively using the 10-wheeler as a bench mark limit. The effect of the increased weights on 6, 10 wheelers, semi trailer and full trailer were examined. The results revealed that the increase in axle weights and number of vehicle passes were the main cause of pavement damages. The first scenario was the worse case of all, associated costs to repair the damages would amount to 132,690 million bahts from 2541 to 2559. The second scenario was the best case of all where the time interval for resurfacing was as planned schedule. For the 3, 4 and 5 scenarios the damages were 126,486 million bahts, 130,368 million bahts and 131,370 million bahts respectively. Further, the results also shown the time intervals for the next resurfacing which are useful for budget planning and resurfacing program.
