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.
How much has the Department of Infrastructure claimed for property damage?
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