Buses are the principal mode of public transport. Bus services are provided by the state-run Sri Lanka Transport Board (SLTB) and by privately run buses. SLTB serves both urban and rural routes. In many rural areas, it provides services in unprofitable areas that would be unattractive to private operators.
Colombo has an extensive public transport system based on buses. The Central Bus Stand in Pettah functions as the primary hub for bus transport in Colombo. The road network in Colombo consists of radial links (or arterial routes), which link the city centre and district centres, and orbital links, which intersect the arterial routes; most bus routes run along the radial links without the benefit of dedicated bus lanes, owing to the high volume of traffic at peak times. A BRT system for Colombo has been proposed, but has yet to be implemented.
Inter-city routes connect many of the major population centres in the country. A few services are available on the E01 Expressway and E03 Expressway. Expressway services use modern Lanka Ashok Leyland buses.
In 2011, the SLTB began introducing new buses to replace part of its aging fleet. These new Volvo 8400 buses from Volvo India, serve on major routes in Colombo city.
The most popular model is the Lanka Ashok Leyland Viking which is operated by both the government owned Sri Lanka Transport Board and several private bus companies.