National Highways will close the A421 in Bedfordshire for two weekends next month to install six massive steel beams for a new bridge as part of its £1bn A428 Black Cat to Caxton Gibbet scheme.
The government-owned company said a new Roxton Road bridge is essential to accommodate the new westbound slip road and eastbound free-flow link from the A421 onto the A1 as the current bridge cannot support these upgrades.
The A421 will be closed in both directions between Renhold and Black Cat roundabout, as well as the existing Roxton Road bridge, from 9pm Friday 1 November to 5am Monday 4 November 2024 and from 9pm Friday 8 November to 5am Monday 11 November 2024.
During the closures, specialist crews will use a 750-tonne crane to manoeuvre six massive steel beams that will form the backbone of the new bridge into place over the A421.
Each beam weighs 130 tonnes and is 37 metres long – ‘approximately the same weight as a fully grown blue whale and length of a Boeing 737 aircraft’.
Once the beams are secured, work will begin on the structure – known as formwork – that will support the surface of the new bridge.
Programme manager Gareth Moores said: ‘The scale and complexity of this engineering feat cannot be overstated and marks a significant moment for our scheme.
‘We understand road closures can be inconvenient, but it’s important to remember that the majority of work so far has been completed while keeping the A421 open to traffic.’
The new Roxton Road bridge with the upgraded Black Cat roundabout in the background
The Black Cat scheme, which is National Highways largest infrastructure scheme currently under construction, will deliver a new 10-mile dual carriageway linking the A1 and A421 Black Cat roundabout in Bedfordshire with the A428 Caxton Gibbet roundabout in Cambridgeshire.
Both roundabouts will be upgraded to free-flowing junctions.
The scheme is due to open to traffic in 2027.
