Manx Utilities says motorists face six months of misery as it improves the capital's sewage system.
Work on a 23-week project on the Old Castletown Road will start on Thursday.
Kewaigue's pumping station will be replaced, and work will take place on the Old Castletown Road and Heron & Brearley brewery site.
There'll be a number of road closures and traffic restrictions between Thursday, April 3 and Wednesday, April 16.
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Repairs on Peel Power Station to get underway
Manx Care doctor survey to be discussed by Tynwald
Weather warning for snow tonight
MHK queries safety at primary school in Ballabeg
Gales put two ferry sailings at risk tonight