The M4 relief road, also known as M4 Corridor around Newport (M4CaN), was a proposed motorway, south of the city of Newport, South Wales, intended to relieve traffic congestion on the M4 motorway.
The Brynglas Tunnels, near Newport, are affected by high peak time congestion
The Brynglas Tunnels carry the M4 under Brynglas Hill in Newport, Wales. The 360-metre-long (390 yd) tunnels are the first and only twin–bored tunnels in the UK motorway network.
The eastern portal: entrance to west bound tunnel on left, exit of east bound tunnel on right