Last updated: 12 June 2018

Where & Why?

Essential safety refurbishment works of the M4 Newport Brynglas Tunnels will commence Monday 20th June 2016 and continuing until mid June 2018.

The refurbishment of the tunnels is required to upgrade the Mechanical and Electrical (M&E) systems, as well as the carriageways, drainage and tunnel linings in order to provide resilience in the tunnel systems for the foreseeable future.

Routine essential maintenance such as tunnel cleaning will continue to be undertaken while the refurbishment works are in progress.

Diversions & Safety Measures

The M4 will be closed between junctions 25A and 26 from 8pm to 6am on up to five nights per week. The A48 Southern Distributor Road in Newport is the dedicated diversion route for all eastbound or westbound traffic. The diversion will be in place between junctions 24 and 28 of the M4; however, local traffic will be allowed to travel up to junctions 25a and 26 in order to access local routes. Closures will usually be in place in one direction at a time; however, closure of both tunnel bores may be needed for short periods of time for safety reasons.

Slip roads leaving and joining the M4 at junction 26 (Malpas) will also be subject to overnight closures. These closures will be restricted to only one slip road at any one time. During any night-time closure of any of these slip roads the motorway will remain in normal operation in both directions.

The current planned closure dates for tunnel refurbishment works and routine maintenance are listed below. Dates may be subject to change for various reasons, such as weather conditions. Additional closures may be required in emergency situations. Latest planned dates and times will be updated in our Home page map, Travel Menu, smartphone apps, Twitter feed @TrafficWalesS or will available by calling us on 0300 123 1213.



Direction of tunnel closure

First date of closure Last date of closure Closure timings Main purpose

Tuesday          12/06/18

Friday          15/06/18 Closures 8pm-6am on weeknights Mondays - Fridays only Tunnel refurbishment works




Further scheme information is available from the Welsh Government website: (external link).

Latest planned dates and times will be updated in our Home page map, Travel Menu, smartphone apps, Twitter feed @TrafficWalesS or will be available by calling Traffic Wales on 0300 123 1213.