The work, which is between the M49 junction with the M4 junction 22 and the M49 junction with the M5 junction 18, and will require full overnight closures on the southbound carriageway between 8pm and 6am.
The work will be completed by the morning of Saturday, April 5.
Highways Agency project sponsor Dave Frampton said:
As part of the Government’s investment in infrastructure, we are ensuring structures like the M49 bridge, properly maintained and safe for road users.
During this work we will be refurbishing the bridge expansion joints, which allow structures to expand and contract with seasonal changes in temperature. This work will lead to improved road conditions for drivers.
The work will be carried out at night to minimise disruption with all closures and diversions clearly signed, but we advise road users to take the work into account when planning their journeys and allow extra time as necessary.
One lane of the M49 southbound will also be closed during the day throughout the work and a temporary 50mph speed limit will be in place for the safety of drivers.
During the closures a clearly signed diversion route will be in place. Road users wishing to travel southbound on the M49 will be diverted to continue on the M4 eastbound to Almondsbury Interchange, then take the M5 southbound to junction 18 to rejoin the M49.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer