Your guide to construction

The newly opened Baron Way and Dove Farm Lane now 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

Since January 2024, we’ve been building the new structures for the three tier Black Cat junction.

We've already constructed two new bridges on either side of the roundabout to carry the A421 flyover.

Meanwhile, we're well underway with preparations for

• the new westbound slip road
• the eastbound free flow link between the A421 and A1

What we'll do next

In the coming months, we’ll change the layout of Black Cat Roundabout as we move into the next construction phase.

We'll start by excavating the the ground where the A1 will run beneath the upgraded junction.

At the same time, we'll realign the section of Bedford Road closest to the roundabout.

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

We've been reinforcing the riverbanks and riverbed to prevent water washing away soil and rock around the structure’s foundations.

This is called 'scour protection'. It will keep the viaduct strong and stable for a long time

What we'll do next

In the next months, we’ll build piers and abutments - the concrete supports that will hold the bridge in place.

Then we'll install the bridge beams. This work is currently scheduled for the end of August.
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At the same time, we’ll continue our scour protection work.

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

We've shifted thousands of tonnes of earth to form the bridge embankments. We've also built the bridge piers and abutments and lifted bridge beams into place on the new structure.

The beam lift was a complex engineering feat:

• we used a 750 tonne crane to lift 8 beams, each 33m long and  weighing 83 tonnes
• we completed the work with minimal disruption over six weekends during National Rail’s Saturday overnight closures

What we'll do next

Over the coming months, we'll install high-strength parapets along the sides of the bridge.

These parapets are essential for the safety of road users. They have to be strong enough to withstand vibrations and the risk of impact from passing trains.

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

If you've travelled along these local roads, you'll have seen the three new bridges taking shape.

We've successfully installed the bridge beams - a significant project milestone in the project. These beams will support the bridge surface. We built them early in our construction timeline to enable our dual carriageway works to proceed efficiently.

What we'll do next 

With the bridge beams now in place, we'll build the bridge embankments. These massive earth structures will support the ends of the bridges.

We'll divert local traffic onto the new bridges as we complete them, while main carriageway construction continues safely beneath.

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 the new Cambridge Road junction to traffic in June 2025. Drivers on the A428 have switched to the new section of road, including the two roundabouts and bridge.

What we'll do next

With the new junction open, we can continue building the dual carriageway beneath it.

We'll continue working on the main road, including the new slip roads, for the rest of 2025 and into early 2026.

When our scheme is complete the existing A428 between St Neots and Caxton Gibbet will remain in place. However, it will be reclassified as the A1428 and B1428 for local traffic use.

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’re constructing a new link between the southern roundabout and Cambridge Road in Eltisley.

This new connection is expected to open in summer 2025. It will give Eltisley direct access to the southern roundabout and onto the A428.

Once our scheme is complete, the existing A428 between St Neots and Caxton Gibbet will be reclassified as the B1428. It will mainly serve as a local route for nearby traffic.

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

The existing south roundabout will remain. We'll build a new roundabout on the north side, linking to the A428 (soon to be reclassified as the B1428).

Access to the service area and petrol station will remain unchanged.

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

What we've done

In June 2025, we diverted traffic from the existing A428 to a new road joining the new north roundabout.

What we'll do next

Through 2025, we'll remove the old, unused section of the A428. We'll also start building:

• the embankments for the new Caxton Gibbet flyover bridge
• slip roads on and off the dual carriageway.

In autumn 2025:

• we'll lift the bridge beams into place on the Caxton Gibbet flyover
• then we'll construct the bridge deck and new road surface