The work, which will continue until November 2015, is needed to replace the foundations of the bridge.
Highways Agency Service Delivery Team Leader, Dave Sledge said:
Keeping our roads, and structures like Piffs Elm Bridge, properly maintained and safe for road users to use is a priority.
We also recognise that the A4019 is an important route for local road users and that is why innovative new working techniques have been developed that will allow repair work to be carried out without closing the A4019 for any length of time.
The majority of works will be undertaken during the day with three narrow lanes installed on a one mile section of the M5 in both directions. A temporary 50mph speed limit will also be in place for the safety of road users and road workers.
The scheme is due for completion by November 2015. The A4019 will remain unaffected apart from three short overnight closures to allow vibration sensitive works to be completed safely.
Work at Piffs Elm is part of a comprehensive maintenance programme on four bridges between junction 10 and 12 of the M5, which started in January.
The foundations of three of these bridges, including Piffs Elm, have been attacked by thaumasite, which is a severe form of sulphate attack and can reduce affected concrete to a soft crumbly material.
Work on the bridges include exposing the foundations and repairing the areas affected by thaumasite. To keep the bridges safe during the work, extra support will be installed to the bridge decks.
Members of the public can find out more about the schemes, including a video on thaumasite, by visiting our M5 Gloucestershire Bridgework Facebook page. Information is also available on the Highways Agency website.
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.