A465 Gilwern to Brynmawr Dualling

Scheme outline

Mostly online upgrade of the existing A465 between Gilwern and Brynmawr 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.

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.

2014 - 2017
Under construction
Other upgrade
for use by all traffic
Highway authority
Welsh Assembly


What's happening on this scheme? You can add a progress update if you know more. Add a progress update
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.

More information


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