Concrete repairs, anti-corrosion and drainage improvements will all be carried out on Horse Bridge until early March 2015.
Lane closures in both directions of the M50 will be in place from Monday, 6 October together with a 50mph speed limit. One lane in each direction will be kept open at all times during the day time.
Around six overnight closures of the M50 will also be needed at times during the project while the roadworks are installed and removed. The dates of these will be confirmed and publicised nearer the time.
Highways Agency project manager Jess Kenny said:
Carrying out this work will improve the longevity of the bridge and improve safety for road users.
Due to the nature of the work there may be some disruption to road users and we advise people to allow extra time for their journeys.
During the full closures, traffic will be diverted from junction 2 of the M50 along the A417 towards Gloucester, the A40 to M5 junction 11 and the M5 northbound to junction 8, where the diversion ends, or vice-versa.
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.