The M4 eastbound was shut for hours between J24 for Newport east and J23A for Magor and Llandevenny in south Wales. Emergency services dashed to the crash near J23A but the three lanes were closed for some time after the crash.
Tailbacks reached J25 for Newport central and St Julians – around an eight mile stretch.
Traffic was busy westbound too due to onlookers. Queues reached J23, the M48 link near Llanfihangel Rogiet.
Diversions, including the A48 eastbound, were congested as a result of the collision, Wales Online reports.
Local roads in central Newport were also busy.
The rural B4245 was slow through Magor as some westbound drivers left the motorway near Caldicot.
It’s understood the caravan overturned in the crash.
Emergency services were at the scene but it is unclear if there were any injuries.