Emergency gas works are causing delays and diversions in Lewisham High Street.
The works, which start today at the junction with Rennell Street, will involve replacing part of the gas pipe.
One lane is closed and temporary traffic lights are in use.
Bus routes 47, 89, 178, 181, 185, 208, 225, 261, 284, 484 and P4 are being diverted due to congestion.
A statement posted on the SGN website on Friday said: "We have ongoing work in Lewisham High Street, near the junction with Rennell Street.
"We've been aiming to repair a gas escape at this location however due to the depth of the excavation, the best solution is to renew a section of our pipework at this location.
"To ensure the ongoing safety of the public and our engineers, temporary traffic lights have been in use. There is also a lane closure and contraflow in place.
"The temporary traffic management needs to remain in position while we wait to start the work. It will also be required during the job itself.
"Our website will be updated once the project is under way."
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