UPDATE 1.20pm: Traffic is now flowing as normal except around the immediate area of the crash.

The inside lane on the M4 east- and westbound at the crash site between junctions 21 (M48) and 20 (Almondsbury interchange - M5) remains closed while surface and barrier repairs are completed.

UPDATE 12.50pm: The motorway and side roads on the Gwent side of the Prince of Wales Bridge are now clear, though a queue of around two miles remains near the crash site.

UPDATE 12pm: The Prince of Wales Bridge is now clear of queuing traffic eastbound (see below - picture, Traffic Wales).

South Wales Argus:

The queue back from the crash site remains at about three miles, though traffic is flowing more easily past that point.

Congestion has also cleared on the A4810 eastbound towards the M4 at junction 23a, and through Magor.

The M48 is also clear westbound, given that the Severn Bridge has now reopened eastbound.

UPDATE 11.30am: Emergency repairs are still being carried out on the M4 between junctions 21 (M48) and 20 (Almondsbury interchange - M5).

Highways England are reporting that the road will not return to normal until 4.30pm at the earliest, though delays back into Wales have eased.

UPDATE 11.21am: The queue eastbound on the M4 has shortened considerably, though remains at about four-five miles.

UPDATE 11am: Traffic remains extremely heavy on the M4 east of Newport,

The queue has diminished slightly, but remains 12-13 miles long and the travel time from junction 24 (Coldra) beyond the crash site approaching junction 20 (Almondsbury interchange - M5) remains around an hour.

UPDATE 10.21am: Eastbound queues continue to stretch back to junction 24 (Coldra).

Side roads also continue to be affected:

  • The queue eastbound on the A4810 towards M4 junction 23a (Magor services) remains more than a mile long;
  • The main B4245 road through Magor is very busy, partly due to a crash earlier near The Flower Shed.
  • The M48 westbound approaching junction 23 has a queue of more than a mile. this is because the M48 Severn Bridge remains closed eastbound as a traffic management measure due to the crash between junctions 21 and 20.  

UPDATE 9.54am: The photo below - from Traffic Wales, shows traffic still queued back eastbound on the M4 to junction 24 (Coldra).

South Wales Argus:

UPDATE 9.47am: A lane has reopened on the M4 eastbound between junctions 21 (M48) and 20 (Almondsbury interchange - M5).

Emergency repairs are currently being carried out both east- and westbound on the M4 at the crash site.

Highways England is reporting that it will be 2pm before the road is open again as normal.

UPDATE 9.40am: The queue of eastbound M4 traffic remains at around 20 miles, back into Newport.

Due to the closure of the Severn Bridge eastbound, the M48 westbound is very busy approaching junction 23, as Chrepstow traffic wishing to go east looks to turn round at junction 23a (Magor services).

A crash is being flagged by Google Maps on the exit ramp eastbound from junction 23a.

UPDATE 9.01am: The crash site is not expected to be cleared until 1pm this afternoon, or shortly afterwards, says Highways England.

Two lanes remain closed eastbound on the M4 approaching junction 20 (Almondsbury Interchange).

UPDATE 8.55am: The Severn Bridge (M48) is closed eastbound as a result of the tailbacks.

UPDATE 8.51am: The main B4245 road through Magor and Undy is very busy as a result of the M4 tailbacks.

AA Travel is reporting the section between Sawyers Bar & Grill and Rockfield Grove is particularly affected.

UPDATE 8.32am: The congestion on the M4 is affecting connecting roads.

There is a tailback of around one-and-a-half miles eastbound on the A4810 - which links with the M4 at junction 23a (Magor services).

UPDATE 8.23am: Highways England are reporting that there is set to be disruption on the M4 until late this morning.

Anyone who needs to get to Bristol or further east and south is advised to take the train if possible. Timetable details can be found here - https://www.nationalrail.co.uk/

UPDATE 8.16am: There have been no injuries as a result of the crash, Avon and Somerset Police have confirmed.

UPDATE 7.58am: The tailback eastbound is approaching 17 miles long, stretching back almost to junction 24 (Coldra) at Newport. 

A CRASH on the M4 north of Bristol is causing long traffic delays and tailbacks for commuters using the Severn bridges.

Traffic reports show two lanes closed on the M4 eastbound between Junction 21 (M48 interchange) and Junction 20 (Almondsbury/M5 interchange).

Highways England reports a vehicle crossing the central reservation. Photographs appear to show the lorry has shed its load of a steamroller.

South Wales Argus: The lorry appears to have shed its load (left), causing long traffic delays on the M4 eastbound out of Wales. Pictures: Highways England (left and bottom right)/Traffic Wales (top right)The lorry appears to have shed its load (left), causing long traffic delays on the M4 eastbound out of Wales. Pictures: Highways England (left and bottom right)/Traffic Wales (top right)

There are currently delays of one hour, and the crash scene is not expected to be cleared until 11am, Highways England reports.

MORE NEWS:

The crash is causing long tailbacks for eastbound traffic on the M4, with heavy traffic on the Prince of Wales Bridge, stretching back beyond Junction 23A (Magor Services).

There is also heavy traffic on the M48 Severn Bridge eastbound, to Junction 2 (Chepstow).

South Wales Argus: Traffic map showing long delays and gridlock on the M4 and M48 Severn bridges, due to the crash between M4 J21 and J20. Picture: The AATraffic map showing long delays and gridlock on the M4 and M48 Severn bridges, due to the crash between M4 J21 and J20. Picture: The AA

More to follow.