A section of the A1 in North Yorkshire will be closed for 34 hours this weekend as a new bridge is installed.
A stretch of the road from Leeming Bar to Barton will shut for the replacement of the Fort Bridge as part of a major upgrade scheme.
The original bridge was demolished last year to allow space for an extra lane to be added.
The £380 million Highways England project, which began in 2014, will replace the existing dual carriageway with a new three-lane motorway which will open in 2017.
The A1 will be closed from 8pm on Friday October 7 until 6am on Sunday October 9 in both directions between junction 51 (Leeming Bar) and Scotch Corner.
A 500-tonne crane will lift giant steel beams weighing 40 tonnes each into place during the closure to create a new bridge at Catterick. Once the new beams have been installed, work can begin to construct the concrete bridge deck.
The bridge links Catterick Garrison in the west to the communities of Catterick and Brompton in the east.
Highways England project manager Tom Howard said:
“This is a significant milestone for the scheme and a complex piece of engineering, which is why it is essential we close sections of the A1.
“We are advising people to plan their journeys, using the many alternative routes that will be signposted off the A1 closure and leave extra time to complete their journeys. We would like to thank drivers for their patience.
“When the whole project is complete, the section of the A1 between Leeming and Barton will be upgraded to a three-lane motorway, tackling congestion and improving journey times.”
Additional work will also be taking place during the closure, including resurfacing one of the slip roads at the Scotch Corner junction.
Drivers who intend to travel on the A1 during the closure are being advised to check the latest traffic conditions before they set off. Clearly signed diversions will be in place and drivers are advised to allow for an extra 30 minutes to their journey time.
Once completed, the A1 Leeming to Barton scheme will create a continuous motorway-standard route between London and Newcastle (including the M1 and A1M).