Highways Agency - Safe roads, Reliable journeys, Informed travellers

The Project

This scheme was one of a number of measures recommended by the London to the South West and South Wales Multi-Modal Study (SWARMMS) to relieve congestion on the M4/M5 around Bristol and was added to the Targeted Programme of Improvements (now known as the Programme of Major Schemes) by the Secretary of State for Transport in December 2002.

Before the improvement, this section of the eastbound carriagway of the M4 suffered from congestion due to the conflict between fast moving vehicles exiting Junction 18 and slow moving vehicles, principally in the inside lane, wishing to continue along the motorway. To tackle this congestion the scheme provides, within the highway boundary, a new climbling lane on the incline and an extended exit slip road at Tormarton. The total length of the scheme is approximately 1.86 miles/3 km.

The Early Contractor Involvement (ECI) contract was awarded to Birse Civils Ltd on 6 April 2004. The Environmental Statement for the scheme was published on 7 October 2004 and a summary of this document (Non-Technical Summary) can be found via the link opposite.

Following the Secretary of State's decision on 1 February 2005, work started on site on Monday 28 February 2005. The scheme was opened to traffic on time on 3 Novemeber 2005 and within budget.

One Year After study

This scheme has been reviewed as part of our ongoing programme of Post Opening Project Evaluation (POPE).  The study compares  the outturn effects of this scheme to the predicted impacts of the scheme.  A summary of the  one year after report is available to download here: M4 J18 Eastbound diverge OYA summary (PDF 51KB).

A full version of the report is available to download here: M4 J18 Eastbound diverge OYA - Full Report (PDF 970KB).