Work has begun in Fulham Road from Gunter Grove, past Chelsea and Westminster Hospital, to the junction with Beaufort Street.
The five-month project is expected to be completed in September 2017.
To help complete the work two-way traffic lights are in place outside Chelsea and Westminster Hospital.
As the work progresses there will be a westbound road closure in Fulham Road from Beaufort Street and a signed diversion will be in place.
Buses will need to follow the diversion and the westbound stops will be closed.
The eastbound bus stop, opposite the hospital, has been relocated east, opposite Limerston Street.
All businesses and shops will remain open.
The work will see the old metal pipes, which have supplied gas for a century, replaced by new pipes made from a more durable material.
The change will reduce the amount of unplanned work required to repair the ageing pipes and ensure a safe and reliable supply of gas to London’s homes and businesses.
Road users are being advised to allow more time for their journey.
Similar work has already been carried out in King’s Road in Chelsea.
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