Projects

Wentbridge Viaduct is a grade II listed structure and one of National Highways’ top ten most important structures on the strategic road network. Opened in 1961 the viaduct carries the A1T, which carries in excess of 86,000 vehicles per day, over the Went Valley.

A three-span post tensioned prestressed box girder bridge, the viaduct comprises six cells supported by inclined reinforced concrete legs with equal side spans of 42.7m and a central span of 57.95m. Driving the need to refurbish the structure were repeated carriageway defects and expansion joint failures stemming from deck waterproofing installed in 1991 reaching the end of its working life.

In addition, National Highways wanted to undertake intrusive testing of the post-tensioned cabling system supporting the bridge to ensure structural integrity was maintained. Octavius was awarded the role of principal contractor under the Scheme Delivery Framework to deliver a challenging programme of work that would encounter significant changes and variations.

Enabling access

Mobilisation included extensive improvements to an unadopted road east of the A1 to enable local residents direct access onto the local authority network while the main works progressed. This allowed safe and unrestricted access to their properties throughout the project.

Octavius’ scope covered delivery of all civil engineering activities to facilitate the replacement of the waterproofing system parapet to parapet, and co-ordination and management of sub-contractors.

The main Octavius’ elements of works were:

• Remove and reinstate concrete verge/kerbing and ironwork
• Remove and reinstate parapet edge beam
• Remove and reinstate safety barrier system in both verges and the central reservation
• Undertake post tensioned intrusive site investigations to determine cable corrosion and voids in ducting system, chloride & half-cell testing of post tensioned cables
• Reseal and dowel existing access chambers
• Inspect, test – and replace if necessary – walkway hanging bolts
• Replace all gullies, including the bespoke connections into the carrier drain running the entire length of the viaduct inside the box structure
• Replace honel drainage through the deck

As the team began work on the viaduct to deliver the original scope it became clear that additional work was necessary to maintain structural integrity. The extent of the variations were such that a full-time planner and quantity surveyor were required to ensure their effective management. The expanded scope included:

• Bridge deck and deck ends below bridge joints required extensive concrete repairs
• Deck defects needed addressing prior to waterproofing
• Safety barrier plinths, originally due for retention, needed to be removed and reinstated to provide uniform safety barrier post height
• Exploratory and previous remedial works led to extensive deck repairs
• Address defects to the hanging bolts supporting the south-bound walkway and access to under deck areas
• Works to walkway hanger bolts required specialist engineering fabricator to undertake replacement and inspection
• Specialist confined space working and rescue team required to enter structure to undertake bespoke drainage gully connections to the carrier drain

Achieving the original and additional scope required a highly flexible approach, and necessitated the highest level of communication with the client, and collaboration with both the client and supply chain.

Creating social value was another essential element of the project. This took the form of renewing and enhancing public spaces in nearby towns and villages including Upton, Kirk Smeaton, Darrington and Little Smeaton; as well as road resurfacing in Wentbridge.

Repairing Wentbridge Viaduct is just one of the ways in which Octavius is creating and renewing transport infrastructure across northern England. To enhance its support for projects and customers in the north of England, Octavius recently established additional offices in Manchester and Leeds. With Octavius having joined RSK in 2025, these offices will allow the team to work alongside fellow RSK Group companies that provide engineering and environmental services for clients in this region. Click here to learn more about Octavius’ projects and customers in northern England.