A465 Gilwern to Brynmawr Dualling

Scheme outline

Upgrade of the existing A465 between Gilwern and Brynmawr, mostly on the line of the existing road but with some off-line diversions, to dual two-lane standard with full grade separation. Most of this scheme lies within the Brecon Beacons National Park, and the road passes through the ecologically sensitive Clydach Gorge.

Geological conditions and the sensitive nature of the site mean the duration of this scheme is longer than for most upgrade projects and the finish date has been put back to 2019 from the original aspiration of 2017.

The main contractor, Costain, was appointed in June 2011.

This is section two of the Heads of the Valleys project, and is likely to be the fourth of the six sections to be completed.

Under construction
Other upgrade
for use by all traffic
Highway authority
Welsh Assembly


23 October 2014

Utility and environmental works have begun, and once legal and design matters have been finalised, a construction start is imminent.

24 December 2014

This scheme officially started on 10th December 2014.

24 January 2015

Traffic Management has now started. Speed limit reduced from 50mph to 40mph. Only one lane in each direction in use.

14 October 2015

Buildings have been demolished along the side road, temporary Bailey Bridges have been installed, and tree removal is taking place. The flyover bridge foundations at Gilwern are taking shape. Rock blasting to commence fairly soon to create the East-Bound carriageway.

4 January 2016

From 9th January 2016 the Glanbaiden Roundabout will be shut. Only 'through' traffic east-west or vice-versa, will be unaffected. Gilwern and Govilon traffic will have to travel to the next roundabout and 'U'-turn to get to their destination. This is to enable the Flyover to be built at this junction.

4 September 2016

Glanbaiden Roundabout is now back open. The flyover is almost complete and is expected to be open to traffic by the end of the year. Various re-alignments of the road have taken place and pre-cast concrete structures are being put in place.

12 April 2018

The road has acheived several major milestones. The Brynmawr Gateway Bridge, the highest structure on the scheme is complete. Several other structures have also been completed. There have been several delays throughout this scheme, due to the geology in the area and also some severe weather issues.

13 September 2018

The Glanbaiden Flyover opened in August, meaning the most easterly section of the scheme will open fully as a dual carriageway towards the end of 2018. This will allow the workforce to concentrate on the difficult section through the Clydach Gorge, finishing there by the end of 2019. Work will then begin on next scheme, <a href="/road-schemes/a465-dowlais-top-hirwaun-dualling">Dowlais Top - Hirwaun</a>.

24 May 2019

A lot of delays on this scheme. As of May 2019, the project is running about 12 months behind schedule. The section is now due to be finished in Autumn 2020.

Road surfacing continues, albeit slowly, and several more bridges have been completed.

More information


With thanks to Matt Tovey and Michael Pritchard for information on this page.