The historical development of the road network in the country dates back to Colonial times when roads were constructed mainly to transport agricultural produce such as Tea and Coffee from plantation areas to the Colombo harbour and for Civil Administration and defence. The roads initially constructed in the country catered for animal drawn carts. With the advent of the motor vehicles in the country in the 1940s, it became necessary to improve the road network to cater for the needs of the motor vehicles.
In the 1950s the main road network of the country was developed and maintained by the Public Works Department. This department was responsible not only for Roads but also for Buildings, Water Supply & Drainage, Housing etc. In the mid 1960s the Public Works Department was responsible only for the Development and Maintenance of the Public Roads and Buildings. In 1969 a major policy change was made and a new Department of Highways was formed solely for the Development and Maintenance of the A, B, C, D and E class roads maintained by the then Department of Public Works, and the total kilometreage of these roads was approximately 28,000 km.
However, this change was short lived, since the Territorial Civil Engineering Organisation (TCEO) was formed in 1971 to take over the major functions of the Highways Department. Upto 1970 the Highways Department and then Public Works Department had fully fledged Bridges Division which undertook the design and construction of all major bridges in the country. However, with the formation of the TCEO another organisation known as State Development and Construction Corporation (SD & CC) was formed to undertake the construction of bridges and other civil engineering works. The functions of TCEO included maintenance and improvements of A, B, C, D and E class roads, maintenance and improvements of Irrigation Works, maintenance and improvements of village tanks, irrigation canals and providing assistance to local authorities for road & bridge improvement works on local authority roads. Although, the Highways Department also functioned during this period, its functions were reduced to planning, design of major roads and bridges and construction supervision of major road and bridge works.
Another major re-organisation of the Highways Sector was effected in 1978 when the TCEO was abolished and functions of the TCEO transferred back to the Highways Department. In 1983 the Road Development Authority (RDA) was formed under the Ministry of Highways incorporated by the RDA Act No 73 of 1981. The functions of RDA at its inception were confined to the execution of selected construction works.
The functions of the RDA were expanded in 1986, when it became the successor to the then Department of Highways. In 1986, the RDA was entrusted with the responsibility of developing and maintaining all classified roads in the country (A,B,C,D and E class roads) totalling upto approximately 28,000 kms of roads and the bridges thereon. In 1989 with the devolution of power under the 13th amendment to the constitution, the C, D and E class roads totalling approximately 17,000 kms and the bridges thereon were handed over to the Provincial Councils. Since then the RDA is entrusted with the development and maintenance of the National Highway Network comprising the Trunk (A class) and Main (B class) roads. The National Highway Network consists of 11, 694 km of roads and 4,048 bridges (span of more than 3m) as at end 2005 including the roads taken over as National Highways during the past few years.