One of the main routes through Ross-on-Wye will be closed to traffic for two months while essential maintenance work is carried out. Greytree Road, Fiveways, will be shut as engineers renew pipework which protects the town from flooding.
The old brick-built culvert links the Rudhall and Chatterley brooks underground.
Engineers will divert the brook along a large pipe placed on the Greytree Road pavement.
The route is the main link between the Hereford and Gloucester sides of Ross.
Many of the town's bus services will need to be diverted and other drivers will have to find alternative routes.