Part of the M23 is set to become a Smart Motorway as part of a 211 million pound project.
This will create a four lane stretch and will allow the hard shoulder to be used for traffic on the motorway – which carries more than 120,000 vehicles every day.
Contractors have been appointed for the scheme from the M25 to Crawley.
The AA has raised concerns and said the “jury is still out” on smart motorways which use technology to control traffic.
However, Highways England said other smart motorways had a good safety record and emergency services could respond quickly if people did break down in a live lane.
The spokesman said “environmentally-sound” smart motorways also cost less than widening schemes and used less land.
But Paul Watters, from the AA, said smart motorways needed to be evaluated after a reasonably long period.
He claimed the Surrey/Sussex scheme would be “permanent all-lane running”, meaning four lanes would in operation all the time, and he added: “We need to see how we’re faring with those.”
Mr Watters added there had been reports of drivers continuing on closed lanes, and surveys had shown people still did not fully understand smart motorways.