Drivers heading away from Gatwick Airport towards the M23 will benefit from an extra lane to reduce congestion from next month.
The Highways Agency will be creating a new segregated left-turn lane for vehicles travelling from junction 9a at Gatwick Airport to junction 9, then joining the northbound M23.
Work on the new lane is due to begin on Sunday (February 21) and is expected to take five weeks, The junction is due to be closed overnight on Monday (February 22), with a diversion route in place.
The Highways Agency said the new lane will ease traffic levels towards the roundabout at junction 9 where the options are to travel south further into Sussex, or north towards the M25 and the capital.
As well as helping drivers and road-users leaving Gatwick, the change will also help traffic from the Horley and Hookwood areas joining the M23.
Peter Phillips, Highways Agency route manager for West Sussex, said: “The new lane will help improve traffic flow around Gatwick Airport and the surrounding area.”
He said: “Whilst the overnight closures at junction 9 are in place, we would ask road-users to allow plenty of extra time for their journeys.”
In order for the new lane to be created, the existing two-lane carriageway will be widened to three lanes on the roundabout.
New signs and road markings showing the new road layout will be put in place. Work will also be carried out on the drainage system and the safety barrier at the same time.
A full overnight closure of junction 9 is due to take place on Monday (February 22) between 8pm and 6am, with a fully-signed diversion, taking in junction 10 of the M23, west to the Tushmore roundabout on the A2011 Crawley Avenue, then north along the A23 London Road through Lowfield Heath to the Longbridge roundabout at Horley, where road-users needing Gatwick can turn around to come back along London Road and join Airport Way.
The Highways Agency said that for the safety of road-users, other than during the full overnight closures, there will be narrow lanes 24-hours a day at the junction throughout the work.
For the duration of the scheme, northbound M23 road-users will not be able to use junction 9 to return onto the southbound carriageway.
They will be diverted to the westbound junction 9a to return on the eastbound carriageway to then travel southbound.
From Monday, March 22, junction 9 will be closed for one week between 8pm and 6am to allow work to take place.
The same diversion route of using junction 10 will apply.