DinahsHollow SoilNailing Landslip RoadInfrastructure

Soil nails replace temporary barriers at Dinah's Hollow landslip route

*Slope stabilisation works at Dinah's Hollow, where steel soil nails and mesh are being installed to reduce landslip risk beside the C13 road. Source: AOL (image by Dorset Council)*

A long-running slope stability problem on the C13 at Dinah's Hollow in Dorset has reached the halfway point of a year-long remediation programme. The road, located near Shaftesbury between Melbury Abbas and Cann Common, has been closed since January while Dorset Council carries out works to reduce the risk of further landslips.

The route is bordered by steep, tree-lined slopes, where previous failures have repeatedly pushed soil and debris toward the carriageway. Temporary roadside concrete barriers were installed in 2015 as a short-term safety measure, but they did not remove the underlying instability. Around 35 tonnes of soil slipped from the east bank in 2016, followed by another smaller failure in 2021, when six to eight tonnes of material fell between the barrier and the road.

This explains why the current scheme is more than a road repair. It is a slope engineering project intended to change how the ground behaves.

The main works involve driving steel nails into the slope face and covering the surface with mesh. Soil nailing improves stability by reinforcing the ground mass, while the mesh helps retain loose material and reduce the risk of local falls onto the road.

Previous landslips at Dinah's Hollow pushed soil and debris toward the carriageway, showing why temporary barriers were not a long-term solution. Source: AOL (image by Dorset Council)

The scheme also includes vegetation clearance, slope reprofiling and drainage improvements. These elements are important because slope instability is rarely caused by one factor alone. Steep geometry, tree loading, weathered soil, water infiltration and poor drainage can combine over time, gradually reducing the factor of safety.

Drainage is especially important at a site like Dinah's Hollow. Water entering the slope can increase pore pressure, reduce shear strength and trigger movement. Reprofiling and drainage works therefore support the soil nails by reducing the forces that drive future failures.

The work has required full road closure between Boundary Road and the B3081, with access maintained for residents and emergency services in some sections. Diversions, one-way systems and temporary 20 mph speed limits have been introduced to manage traffic through nearby villages. Recent heatwaves have also affected working patterns, with teams extending working hours into cooler parts of the day and using weekends to keep the programme on track.

The project is expected to finish by the end of December. Once complete, it should provide a more permanent solution than the temporary barriers previously used on the route. For Dorset, Dinah's Hollow is a reminder that rural roads can carry serious geotechnical risk, especially where steep cuttings, vegetation and groundwater interact beside narrow carriageways.

Sources: www.bbc.com, dorsetcouncil.gov.uk, aol.com