A428 Black Cat junction takes shape as major construction milestone reached

Skanska working on behalf of National Highways on the A428 Black Cat to Caxton Gibbet improvement scheme has lifted and installed 15 steel beams that will support the new bridge structure for the Black Cat junction flyover. Watch the video of the install here.

Each beam was delivered to site under police escort and lifted into position on the same day. The first 10 pairs of beams, measuring 38 metres long and weighing around 60 tonnes each, were installed on the west and central sections of the flyover. The remaining five beams, which weigh approximately 30 tonnes each and measure 18 metres long, were then installed on the eastern side of the bridge. A 650-tonne crane was used to carry out the complex lifting operation.

Building the flyover

The Black Cat flyover is the final major structure on the improvement scheme and it will connect the new 10 mile dual carriageway through the junction.

With the beams now in place, the project team can begin the next stage of construction, including building the bridge deck and completing the permanent connections.

Due to the bridge's angled design and the alignment of the A428 approach road, temporary support structures were installed as each beam was placed. These large support frames, known as Megashores, provide stability while the steel beams and concrete bridge deck are being constructed.

The temporary supports help control movement during construction and will be removed later this year once the beams have been permanently connected to the reinforced concrete bridge supports. Now the beams are in position the excavation works to the new A1 underpass can commence. The new 10 mile dual carriageway will open Spring 2027.

Keeping traffic moving

Throughout construction, extensive planning and carefully managed traffic switches have helped minimise disruption for road users.

The main structures at Black Cat junction have been built while keeping the surrounding roads open, with the majority of works taking place during normal working hours.

Cementation Skanska delivered all the piling works for the major structures within the junction area, including the flyover foundations and secant retaining walls. At peak activity, four piling rigs were operating simultaneously across three structures to support the challenging construction programme.

Neil Davison, Project Manager at Skanska, said: "The installation of these bridge beams marks a major milestone for the A428 Black Cat to Caxton Gibbet project and is a testament to the dedication and commitment of the entire integrated project team.

"Careful planning and the successful delivery of multiple traffic management phases have enabled us to create safe working areas and prepare for the next stage of construction. This has required close coordination between our structures team, supply chain partners and many other specialists working across the site.

About the A428 Black Cat to Caxton Gibbet project

The A428 Black Cat to Caxton Gibbet improvement scheme will upgrade approximately 10 miles of the A428 between the Black Cat roundabout near St Neots and Caxton Gibbet roundabout in Cambridgeshire.

The project includes:

• A new 10-mile dual carriageway.
• Two new major junctions.
• 32 new structures including 18 bridges.

Once complete, the scheme will reduce congestion and improve traffic flow, delivering more reliable journey times and greater safety for road users. Support economic growth across the region and Improve connections between local communities and key employment areas. Create a more resilient road network for future travel demand.