Detailed Design Study for this 28 km stretch was commenced in July 2001 under a grant aid assistance from Government of Japan.

The expressway will be Sri Lanka's costliest and most expensive road, estimated at US$57 million per km[6] In January 2013, Road Development Authority said that there will be an extra interchange in Athurugiriya with the intention of accommodating projected traffic from a fast developing area.

[7] The construction of first stage from Kottawa to Kaduwela, a length of 11 km, was completed at a cost of Rs.

[5][9] Construction of the second stage of the project from Kaduwela to Kadawatha, a length of 9.8 km, began on 18 February 2012.

[5] The second phase is scheduled to be opened on 20 June 2015 and will form a major connection between Colombo and Kadawatha and a link to the Northern Expressway which will begin construction in July, thereafter connecting the capital with the major tourism cities: Kandy, Kurunegala and Dambulla.

In January 2013, the third phase construction contract of this project from Kadawatha to Kerawalapitiya (length of 9.2 km) was awarded to China Metallurgical Group Corporation Limited by the Cabinet of Sri Lanka for a value of Rs.