Cumbra's B5289 to close for emergency repairs
The main road into Borrowdale from Keswick is to close in both directions for six weeks, Cumbria Council has said.
Saturated foundations are falling away beneath the B5289 near the turn off for Watendlath.
The emergency work is due to begin at 10:00 GMT on Monday with a diversion set up over the Honister Pass and via Buttermere, Lorton and Whinlatter.
Pedestrians, dismounted cyclists and horse riders will be able to pass.
The council also anticipates increased traffic along the back road via Portinscale and underneath Cat Bells to Grange.
The council's school transport team is liaising with bus operators, Keswick School and Borrowdale Primary to ensure that suitable arrangements are in place for next week.
Keith Little, Cumbria Council's cabinet member for highways, said: "While we did all we could to do this essential work on the retaining wall and keep one lane open, we now know that this cannot be done safely."