A lane closure on the B2145 at Hunston is continuing to cause heavy delays in the surrounding area.
Traffic backed up in roads around the closure and on the A27 bypass this morning through rush hour due to the gas works.
Congestion is still reported through Stockbridge and Donnington as motorists avoid the closure, which runs from Whyke roundabout to the B2166.
A new gas connection is being laid along the road.
West Sussex Highways has said the works are too complex to be completed at night and a signed diversion is in place through Chichester Road, Selsey Road and the A27.