A stretch of the eastbound M4 motorway has been closed at Newport until Monday morning as the Brynglas tunnels upgrade continues.
Eastbound traffic is being diverted via the A48 Southern Distributor Road between M4 junctions 28 and 24.
The tunnel, between junction 26 at Malpas and junction 24 The Coldra, closed at 19:00 BST on Saturday and will reopen on Monday at 06:00.
The Welsh Government, which said the upgrade would finish in spring 2018, said the tunnels were built under old design standards and were no longer compliant.
The Usk River bridge and Malpas junction viaduct, either side of the tunnels, also require maintenance.
Scheduled Brynglas Tunnels weekend closures
- 19:00 16 September - 06:00 18 September
- 19:00 23 September - 06:00 25 September
- 19:00 7 October - 06:00 9 October