The Outer Circular Highway (OCH) to the City of Colombo is a new access controlled highway, linking Colombo – Katunayake Expressway (CKE) and Southern Transport Development Project (STDP). It is 10 – 15 kms away from the City Centre and 29.10 kms long in total. It will connect the North and South more quickly as a by-pass to the Colombo City and disperse the traffic from / to Colombo more effectively, resulting in easing traffic congestions in the Colombo Metropolitan area.
| Length | 11.0 km |
| Width | 4-lane access controlled Highway |
| Design Speed | 100 km/hr |
| Structure | 5.5km Viaduct With Long Span – Design Review and Construction Supervision |
Southern Section: Kottawa to Kaduwela (11.0 kms) including 5.5km Viaduct
The Southern Section of the Outer Circular Highway has a length of 11.0 km and is a 4-lane access controlled Highway with 2 interchanges. The project consists of 2 long bridges and 15 nos. viaducts of total length 5.5kms. The balance section is on an embankment fill of which 3.10km is on soft ground. The soft ground treatment methods adopted consist of Gravel Mat, Band Drains, Geotextiles, Rock Replacement and Gravel Compaction piling.
