Emergency traffic lights have been installed for a section of the A6 at Shap following a partial wall collapse.
A retaining wall just south of the summit has collapsed.
As a safety measure, one lane of the road is currently closed and two-way traffic lights have been installed.
Westmorland & Furness Council said investigations had started to determine and how to prevent any further collapse and how to fix the issue.
The lane closure will remain in place while the work is carried out.
Drivers are advised that there may be some delays to journey times through the traffic lights.
