Hamad I. AI-Abdul Wahhab, and Saad A. Aihan




 Over the past two decades, Saudi Arabia has initiated--massive construction program to modernize and improve its highway network. In the short span of 20 years, Saudi Arabia has built an impressive highway network which includes more than 5330 km of express and dual highways, more than 37,670 km of single roads with two lanes, and over 85000 km of agricultural roads in addition to a massive urban road network at a total cost of more than 120 billion Saudi Riyals (32 billion US $). Roads are designed to the best international standards for service lives of 15 to 20 years before they need any major maintenance. However, during the past few years some of these roads have experience excessive failures such as rutting, raveling, depressions and fatigue at early stage of the pavement's life. The rate of deterioration of pavements has been augmented by the increasing traffic, axle loads and tire pressure, lack of good quality materials, high water table, and harsh environmental conditions.

Several research projects have been carried out by concerned agencies such as King Abdulaziz City for Science and Technology, Ministry of Communications, and leading universities in the Kingdom to identify possible causes and remedies. Studies indicated that the problem can be eliminated by trucks weight and tire pressure control, improvement of