Temporary traffic lights put up in Wherstead Road, Ipswich caused major rush-hour delays this morning.
There were long tailbacks in both directions near to the Wherstead Road junction with The Strand.
Traffic was reported to be queueing back to the town centre and to Tattingstone in the opposite direction.
The work is being conducted by Anglian Water and is due to be completed tomorrow.
Motorists are advised to avoid the area if possible.
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