Drivers are warned of due to the earlier accident on the M4.
Congestion is stretching to the Second Severn Crossing toll booths. Travel time is between 45 and 60 minutes.
All all lanes re-opened at 4.55pm.
TWO lanes are blocked and queueing traffic reported for four miles due to a crash on the M4 in Newport.
The incident, involving three vehicles, happened on the westbound stretch around half a mile west of J24 between the Coldra and J25 at Caerleon.
Congestion is stretching to J23a at Magor Services.