Your guide to construction

Last year we opened Baron Way and Dove Farm Lane to form the new Roxton Road link. This provides a vital connection between Roxton Road and The Lane in Wyboston.

This new route improves access to the A1/A421 Black Cat roundabout and also serves traffic from Nagshead Lane and Chawston Lane.

To support this upgrade, we've permanently closed direct access to the A1 northbound from:

• The Lane
• Nagshead Lane
• Chawston Lane

We previously identified these junctions as safety risks. Their layouts required drivers to merge directly into fast moving A1 traffic.

We designed the new Roxton Road bridge, opened to the public in early May, with safety and accessibility in mind: 

• it accommodates pedestrians, cyclists, and horse riders
• it also supports a new westbound slip road as well as an eastbound free flow link between the A421 and A1

We'll also relocate pedestrian access to bus stops on both the northbound and southbound A1 as part of these improvements.

We’re transforming the Black Cat roundabout in Bedfordshire into a modern three tier junction. It will seamlessly connect the A1, A421, and surrounding local roads:

• A1 traffic will flow freely below ground through a new purpose built cutting
• A421 traffic will travel over the junction on a new flyover
• local roads, including Bedford Road, will remain at ground level, making it easy to connect between routes.

These improvements will reduce congestion, making journeys quicker, safer and more reliable for everyone.

What we've done

We've made significant progress around the Black Cat junction.

We've built two new bridges on either side of the roundabout to carry the A421 flyover - a key scheme milestone.

We've also opened new road links:

A421 eastbound free-flow link

Drivers can now join the A1 northbound without needing to stop at the roundabout.

A421 westbound on-slip improvements

Two lanes are now open for traffic heading towards Bedford and the M1.

Bedford Road realignment

We've carefully repositioned the road while keeping it open to traffic. This will help us minimise disruption during construction.

What we'll do next

We'll start building:

• the three bridges that are key parts of the central flyover
• the new junction layout.

Once these bridges are in place, we'll start excavating the new A1 underpass.

As part of the new 10‑mile dual carriageway, we’re constructing a 240 metre viaduct over the River Great Ouse.

The viaduct will bridge the river near the Black Cat roundabout between Roxton and Little Barford.

What we've done

In December 2025, we  finished installing the bridge structure for the River Great Ouse viaduct - a major engineering operation.

We carefully lifted 20 large bridge beams and 485 smaller crossbeams into position - a total weight of more than 2,000 tonnes.

Assembling the structure safely required precision planning and co-ordination.

What we'll do next

We're building the bridge deck that will carry traffic across the viaduct.

This involves a combination of carefully planned concrete pours and specially manufactured deck panels.

If you're travelling around the Black Cat roundabout, you may see our 300-tonne crawler crane at work. It's lifting deck panels into position, each weighing around 20 tonnes. We'll install 340 panels in total.

We expect to  finish this work by late spring 2026.

A new bridge will carry thousands of drivers safely over the the East Coast Main Line railway.

This railway is one of the busiest in the UK, running north to south between London and Edinburgh.

What we've done

By early 2026, we finished work on the reinforced concrete deck and parapets.

This marks the end of main structural work on the bridge -  a significant milestone.

At the same time, we built approach embankments on either side up to the bridge structure. 

What we'll do next

We'll continue building the new road that will run over the bridge.

We'll instal kerbs, drains and safety barriers, then lay the road base and surface.

As part of the new 10‑mile dual carriageway, new bridges will carry these roads over the main route. This allows local traffic to move uninterrupted over the new dual carriageway below.

What we've done

We've completed new bridge structures at Barford Road, Potton Road and Toseland Road. 

Now we're building the embankments that will link each bridge to the new local roads.

What we'll do next 

At Barford Road, well continue building the embankments on either side of the new bridge into early summer.

At Potton Road, after finishing utility diversions and installing drains, we've started connecting the new road with the existing network.

At Toseland Road, we're installing drains and surfacing the new road.

We’re building a new junction at Cambridge Road, just east of St Neots. Two ground-level roundabouts are connected by a bridge over the dual carriageway that runs in a cutting below.

The new junction will provide better access to the town centre and train station.

Drivers can now join or leave the new dual carriageway at this junction, making journeys faster, easier, and safer.

What we've done

We opened new Cambridge Road junction to traffic in June 2025.

We've also finished all surfacing and utility diversions.

We've installed new fencing and seeded grass along the former A428 alignment. The grass is growing well.

What we'll do next

We'll install new road lighting and start building the slip roads.

Then we'll remove the existing section of road, making way for the new dual carriageway under the bridge.

Finally, we'll install safety barriers. We'll also topsoil and landscape the junction.

We’re improving the road layout at Eltisley with the same type of junction we're building at Cambridge Road, St Neots. Two ground‑level roundabouts are connected by a bridge over the new dual carriageway.

These roundabouts, along with the closure of the B1040 St Ives Road junction, will greatly improve road safety. Importantly, there'll be no direct access to the new dual carriageway at Eltisley. The nearest junction will be 1.5 miles away at Caxton Gibbet.

What we've done

We opened the upgraded Eltisley layout to traffic in April 2025, making journeys safer for people using the A428 and B1040.

What we'll do next

We'll finish work on the new footpath on the north-east side

We'll complete kerbs and drainage along the A428 between Caxton Gibbet and Eltisley.

We'll continue work on the north-west arm of the junction and finish fencing.

We're transforming the Caxton Gibbet roundabout in Cambridgeshire into a modern, two-level junction. It will seamlessly connect the new A421 dual carriageway with the A428 and A1198:

• traffic on the new dual carriageway will flow smoothly over the junction on a newly constructed flyover bridge
• local traffic between the A428 and A1198 will continue to use the ground-level roads

This upgrade will allow drivers to join or leave the new dual carriageway at Caxton Gibbet.

What we've done

We've moved traffic off the Caxton Gibbet - Cambourne contraflow.

Drivers can now use the Caxton Gibbet North roundabout to reach the new section of road.

This allows us to start building the new eastbound off-slip road.

Meanwhile, we've successfully installed bridge beams on the new flyover and started building the bridge deck.

What we'll do next

We'll start installing drains and surfacing the bridge that will take the new dual carriageway over the junction.

We'll continue diverting utilities throughout early 2026.

We need to finish these works before the next construction phases, which include the new south roundabout.