The outer Circular Highway (OCH) is located in the Colombo Metropolitan Region and passes through two administrative districts, namely Colombo and Gampaha. This highway runs around 20 km away from the City centre of Colombo, connecting radial routes and has a total length of 29.2 km. The northern end of the highway is located at Kerawalapitiya on Colombo-Katunayake Expressway and the southern end is located at Kottawa on Colombo-Ratnapura-Wellawaya-Batticaloa (A004) road where Southern Expressway meets OCH.
The OCH is to be developed as a 4-lane Highway with provision for future expansion to 6-lanes. The design speed of the Highway is 100 kmph.
The expressway is implemented in three phases as given below;
Phase - 1
Section from Kottawa to Kaduwela
Phase - 2
Section from Kaduwela to Kadawatha
Phase - 3
Section from Kadawatha to Kerawelapitiya
OCH Map as at 01 October 2013
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To minimize traffic congestion and encourage development away from the highly populated urban areas in the Western province achieving better balance for growth.
To provide an effective bypass for North-South bound traffic and to reduce through-traffic in the city of Colombo.
To provide passenger transport to destinations in a minimum time period.
To provide a quick passenger and good transport facility from airport.
To encourage foreign investors by reducing travel time by improving infrastructure facilities.
To minimise environmental impacts created by burning of fuel due to traffic congestion.
To encourage the development of current or future growth centres by providing connections in between.
Servicing of relatively short-distance trips between existing and future growth centres.
Quick development of interchange areas will increase property value and creation of new employment opportunities.