Diversions put in place for £950m road plan

The new road layout by the A428 Black Cat is due to be finished by 2027

A 12 mile (19km) diversion will be put in place over several nights as part of work on building a £950m new road and junction.

National Highways said the A421 would be shut from 21:00 to 06:00 BST over nine nights, starting from Monday.

It would allow preparations to begin for the improvements on the A428 Black Cat route from Bedfordshire to Caxton Gibbet, in Cambridgeshire.

Safety barrier, 40mph speed restrictions, narrow lanes, speed cameras, CCTV and signs will be installed.

The current Black Cat roundabout on the A1 will be removed as part of the scheme and replaced with a flyover

The existing central reservation will be converted into a running lane, which will keep two lanes open on the A421 eastbound throughout construction, it said.

Gareth Moores, programme manager, said: "While it won't always be possible to completely avoid some short-term delays and congestion, we have looked at lots of different scenarios and outcomes to keep traffic moving as much as possible during construction. 

"I know from speaking to local people and businesses there is overwhelming support and anticipation for the start of construction."

The new 10-mile (16km) dual carriageway will link the A1 Black Cat roundabout to the Caxton Gibbet roundabout on the A428.

It is expected to be finished in 2027.

Main construction work is due to start by the end of the year

There will be eastbound overnight closures from 21:00 to 06:00 from Monday to Thursday and on 23 to 24 October.

The westbound carriageway will be shut at the same time from 25 to 27 October.

The diversion route will be in place from the A421 via Cardington, Moggerhanger, to the A1 at Sandy.