The Westlink road in Belfast is a dual carriageway. The Westlink was originally planned in 1964 as the Belfast Urban Motorway, the route was to have been fully grade-separated and would have completely encircled the city centre. Due to lack of money and public opposition only the western portion was completed and this was originally not fully grade-separated.

The entire road was built to dual two-lane standard. The southbound section from Grosvenor Road to Broadway was widened to three lanes in 2002. Major upgrade work completed in 2009 extended the third lane to the newly completed Broadway underpass, where the road now seamlessly merges into the M1 Motorway.

The underpass opened on Friday 4 July 2008. On Saturday 16 August 2008 it completely filled with water due to several hours of torrential rainfall. This earned it the nickname ‘The Wetlink’.

The Westlink was built in two phases. Phase 1, connecting the M1 at Broadway to Grosvenor Road opened in February 1981. Both of these junctions were built as at-grade roundabouts, with a traffic-light junction serving Roden Street and Mulhouse Road half way between. Phase 2, extending the scheme from Grosvenor Road to York Street, was completed in March 1983. This section has two grade-separated junctions at Divis Street and Clifton Street and passes under Peter’s Hill. The York Street terminus is at-grade and links to the M2 and, since its opening in January 1995, to the M3.