Motorists are being warned to find alternative routes ahead of the closure of part of the M4 motorway so a new footbridge can be installed.
The major thoroughfare will be shut off between Junctions 13 and 14 from 1900 BST Saturday until 0700 BST on Sunday.
The new footbridge will replace the one that was demolished in March, as part of an ongoing improvement scheme at Chieveley junction in Berkshire.
Sign posts along the route will show alternative routes for drivers.
John Martin, project manager, said: "The alternative route from Bristol would be to come off at Junction 14, down the A338, then onto the A4 Bath Road and then back up the A34 to junction 13."