Island Roads | Modern solutions restores road through Victorian Town

A complex scheme to reconstruct a picturesque road in the Victorian seaside town of Ventnor on the Isle of Wight has been completed almost three years to the day the section spectacularly collapsed.

The project – one of the most complex undertaken on the Island – used local and national expertise to overcome challenging local geological and physical features to restore what is an important and unique piece of local infrastructure.

Leading the project was Island Roads which supplies highway maintenance service to the Isle of Wight Council

In January and February 2020 the Victorian age masonry wall supporting Belgrave Road in Ventnor failed following a period of heavy and sustained rainfall.

Island Roads’ initial priority was to ensure the safety of those in buildings and businesses above and below the failed 150-year-old wall with some temporary evacuations required because of the risk of further collapses and cascading debris.

In a first for the Island, specialist heavy-duty netting was installed across the failed slope as part of a risk-management plan developed to protect members of the public. Specialist roped access teams removed by hand some of the debris deemed a possible risk. Island Roads also co-ordinated diversion of all services away from the failed wall section.

The next phase was survey and investigation work to determine the likely cause of the failure which in turn could inform the process of designing a solution to rebuild the retaining walls and re-open the road. Atkins were engaged to compile a Root Cause Analysis, Scope of Works for Ground Investigation and then Detailed Design, production of Construction documentation and site support during construction.

As part of the risk mitigation measures, Island Roads installed 20 automated tiltmeters across the site, to monitor in real time movement across the potentially unstable site.

The survey work lead by a project team of Isle of Wight Council, Island Roads and consultants Atkins, together with specialist contactors SOCOTEC and Corefix, was shortlisted for the award of Ground Investigation Project of the Year at the 2021 Ground Engineering Awards.

In developing the remedial and reconstruction plan, Island Roads and Atkins were presented with a number of challenges including how to replace non-safety compliant historic masonry with an alternative that satisfied the need of conservation officers. Furthermore, the nature of the failure and the local road pattern severely restricted the size of plant that could be utilised to construct a remedial solution.

In addition, the failed masonry block was considered unstable requiring careful demolition as part of the reconstruction works.

With piling not an option due to the size of plant required, a soil nail solution was adopted as this allowed installation with small scale and hand-held plant. The facing was designed as a cut stone facing on reinforced concrete. The masonry parapet was specified to meet current containment requirements for both vehicular and pedestrian highway users. This engineered solution was the optimal choice given the site constraints. The top-down soil nail installation –- not only provided stabilisation of the slope in the temporary situation but were designed as the permanent works solution with the reinforced concrete wall construction, back fill, and masonry cladding being constructed in reverse from the bottom up once the site was made safe.

Local company Stoneham Construction won the contract to undertake the build and work began in December 2021. Another local company, Corefix, were also engaged to install nearly two kilometres of steel soil nails to support the new and existing walls. Construction was completed in December 2022.

Island Roads senior project manager Jason Boulter CEng MICE said: “What was particularly pleasing was how well all the parties, Island companies at the forefront, worked together to overcome the inherent problems and provide a solution to a pretty unique set of circumstances.”

For further information, please contact info@islandroads.com or visit www.islandroads.com