Work will begin on changes to Welshpool's one-way system on Monday, April 29.
Traffic Wales gave an update on the road works, which will affect the A458 and other local roads, revealing that the work will take around 10 weeks.
Previously, the work was expected to last between six and eight weeks.
Traffic Wales also said that there will be some night closures on the A458 from Church Bank to Salop road, and a closure of Brook Street into Church Street, and that prior notice will be given.
Welshpool's main street is set to be reduced to a single lane to improve safety, the Welsh Government said.
The scheme will also see a zebra crossing built near the town hall and Brook Street and Union Street returning to two-way.
A consultation document by the Welsh Government said the move was designed to improve pedestrian safety as well as curbing inappropriate driver behaviour on Broad Street.
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