It will be closed between 8pm tomorrow evening (September 24) and 6am the following morning (September 25).
The public is advised to not be alarmed by smoke, sirens and flashing lights may be visible/heard in the area around the tunnel.
What diversions are in place?
🚒Emergency Service Exercise🚒
📍#M4 Brynglas Tunnel closed in both directions overnight⛔
📆24/09/24 – 25/09/24 |⌚20:00 – 06:00.
🚨Smoke, sirens & flashing lights may be visible/heard in the area around the tunnel. Please do not be alarmed, this is part of the exercise. pic.twitter.com/J5rLma2hyW
— Traffic Wales South (@TrafficWalesS) September 23, 2024