Following several studies in late 1980, Colombo-Matara Expressway concept was introduced accepting the fact that development of southern corridor would enhance the uplift of the country.

In 1997, the Government of Sri Lanka obtained financial assistance from the Asian Development Bank and carried out feasibility study in 1998.

The Funding Agencies, Asian Development Bank (ADB) and Japan Bank of International Corporation (JBIC) agreed to provide the funding for the STDP. Section from Kottawa to Kurundugahahetekma (65 km) was undertaken by JBIC and section from Kurundugahahetekma to Godagama (64.8 km) was undertaken by ADB.

In 2007, a restructuring of contract was necessitated due to increased work scope and ADB’s funding is limited to the section from Kurundugahahetekma to Galle (30 km) including Galle Port Access Road.