The M48 Severn Bridge will be closed this weekend for maintenance work, according to the Highways Agency.
The closure runs from 06:00 on Saturday morning, until 18:00 on Sunday.
Traffic is being diverted to the M4 Second Severn Crossing.
Chris Pope, from the Highways Agency, said: The Severn Bridge is a vital transport link between England and Wales, and this work will help keep it operating safely for many years to come.
"We planned the work carefully to cause the least possible disruption to road users and will also be taking the opportunity during the closures to carry out other work ... to reduce the need for traffic management in the future.
"The work is being carried out when traffic flows are lowest but road users are advised to plan ahead and allow longer for their journeys."