To solve this problem, the Sri Lankan government expects to adopt the mechanistic-empirical design system for new or overlay thickness design of pavements, especially for low-volume roads. This situation has caused a shortage or overuse of materials. This may also result in over-estimated or under-estimated catalogues of the current pavement design guide without any consideration of the structural capacity of a pavement system. As a result, a large amount of in-situ soil and aggregates available in the country have not been used as roadway construction materials in the context of optimum quantity. Road networks in Sri Lanka are structurally designed according to Road Note 31, which restricts the indirect material property to a specified-limit of the California Bearing Ratio value. This situation has caused shortage of materials such as aggregates and as a solution the government expects to adopt the mechanistic-empirical approach for a road pavement thickness design. The empirical methods restrict the material properties to specified limits and as a result, most of the soil and aggregates available in the country cannot be used for the road construction in an optimum way of usage. The current road pavement designs are based on empirical methods, based on Road Note 31, published by the Transport Research Laboratory about 30 years ago. The Road Development Authority of Sri Lanka is responsible for building, operating and managing national roads and expressways and provincial road agencies and local authorities are responsible for provincial and rural roads. The government plans to build another 200 km length of expressways and to rehabilitate around 6,000 km of road within the next five years. A prerequisite for this is an improved transport system and investments in the road network have been intensified.ДЇor the last 9 years more than 10,000 km of roads were rehabilitated and around 150 km of new expressways were built.

The government strives to, and encourages, continued growth. OverviewДuring the last nineВ years, the Sri Lankan economy has grown rapidly. A preliminary study in Sri Lanka provides important insights into mechanistic-empirical pavement thickness and overlay design for roadway networks.

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