The A428 Black Cat to Caxton Gibbet improvement scheme has reached a significant milestone with the successful installation of the River Great Ouse viaduct beam, the longest structure on the project at approximately 250 metres.
Between October and December, the project team installed 20 large viaduct girders and 485 smaller crossbeams, placing a total of 2,067 tonnes of UK manufactured steel onto permanent bearings.
Steel deliveries were scheduled overnight, typically around 2:00am, to minimise disruption to the local community.
In this timelapse video Agent Sean Chapman explains the process.
The River Great Ouse viaduct will form a critical part of the new 10-mile dual carriageway between Black Cat and Caxton Gibbet, carrying vehicles safely over the river.
Following completion of the steel installation, work has now begun on constructing the concrete bridge deck. This phase combines in-situ stitches with precast concrete deck panels, which are manufactured off-site in controlled factory conditions to ensure quality and consistency. Off-site manufacturing also supports the project’s sustainability goals by reducing carbon emissions, waste and water consumption.
A 300‑tonne crawler crane is being used to install the precast panels, each weighing approximately 20 tonnes. In total, 340 panels will be lifted into place, with deck installation expected to be completed by early May.
The team has continued to work through challenging conditions, including high rainfall and operations around the river environment.
A428 Project Director Dan Trathen said: “Reaching this milestone on the River Great Ouse Viaduct is a fantastic achievement for everyone involved. The hard work and determination of the team has been outstanding. From complex steel installations to innovative off-site construction, their efforts have kept the project moving forward safely and efficiently. Every milestone brings us closer to improving connectivity for the region, and I’m incredibly proud of the teamwork driving this project forward.”
The successful completion of the beam lifts marks an important step forward in delivering a safer, more reliable road network for the region.