The main road linking Monmouth and Chepstow will be closed from Monday (1 March) for six weeks, while crews deal with fractured and falling rock to ensure road user safety.
The A466 Wye Valley just north of Bigsweir Bridge will be closed around the clock until 9 April so the rock can be scaled back, pinned and netted. Following the completion of the works in April, the road will be re-opened for two way traffic.
Although the road runs between the two Welsh towns, the section in question is just across the 'sylvan' Wye in Gloucestershire.
'A rock embankment above the road is fractured and sections are falling onto the highway below. The rock poses a danger to the road and vital improvement works are required to ensure the safety of motorists,' Gloucetershire Highways said.
The design and construction works are estimated to cost around £150,000.
Gloucestershire County Council’s highways maintenance contractor, Ringway will be undertaking the work as the principal contractor, while Atkins will be providing design support.
The news follows the winter storms in February 2020, when a shallow landslide appeared just north of Bigsweir Bridge on the southbound side of the A466 carriageway.
Highways teams removed the slipped material, and installed traffic lights with concrete barriers to provide temporary protection to the carriageway.
The council said: 'There were a significant number of storms last winter meaning multiple sites needed to be mitigated across the county. To design and install suitable remedial measures the site conditions needed to be fully understood. As it was possible to keep the road open with traffic management this was not seen as essential work during the first COVID-19 lockdown.
'Once the lockdown eased, we were able to undertake a more detailed site survey and continue with the design. As the area is within a conservation site there are particular ecological and environmental permits and processes that need to be completed and adhered to before site works can commence.'
The latest work will involve scaling the embankment back to remove loose rock and soil. It will then be netted and pinned to help prevent any rock falling in the future.
Cllr Vernon Smith, cabinet member for highways and flood, said: 'In the interest of public safety, it is necessary to close this road while our crews undertake the dangerous task of scaling back the fractured rock.
'I understand the closure is going to cause inconvenience for drivers and local businesses, however this work is significant and much-needed to ensure local residents and visitors from outside of the county remain safe on Gloucestershire’s roads.”
Cllr Patrick Molyneux, county councillor for Sedbury, said: 'The A466 is a popular commuter route into Gloucestershire and I’m sure you’ll agree the rock embankment above the road is in need of some urgent attention. Please remember to plan your journeys around these closures, as there may be delays and changes to bus times.”