An £18m programme of sewer works will close one lane of traffic on a major Lancaster city centre road for four weeks.
The lane closure will be on Bulk Road outside Parliament Street Retail Park from Monday, August 5. St Leonardgate will also be made temporarily one way from Bulk Road to Rosemary Lane.
Phoenix Street will also be closed to all traffic.
United Utilities said the closure is to allow a brand new underground storage tank at Parliament Street Retail Park to be linked into the existing sewer beneath Bulk Road.
The tank will be used to capture the extra volumes of dirty water that flood into the sewers during heavy rain – meaning it won’t have to spill into the River Lune.
The overall sewer project aims to clean the River Lune and improve Morecambe’s bathing waters.
Dawn Harrington, project manager, said: “We’re sorry for any disruption this may cause. We have been liaising with the council and many other agencies to help make sure we keep traffic moving.”
United Utilities is also carrying out some modification work at several junctions, realigning kerbs and resurfacing, to make sure the diversion routes operate as smoothly as possible.