Variable motorway speed limits designed to improve road safety and help reduce congestion have been proposed for Kent.
The scheme, for the M25 between junctions 2 and 3 and the M20 from junction 4 to 7, is similar to one on the M25 between junctions 10 and 16.
Traffic sensors calculate optimum speed limits to keep traffic moving and these are displayed on overhead gantries.
The Highways Agency said crashes fell by 10% under the existing scheme, which runs from Surrey into Buckinghamshire.
The Highways Agency said the existing scheme, which began in 1995, had allowed it to manage traffic "proactively" by slowing down traffic or closing lanes during an incident to prevent further collisions.
Highways Agency regional performance manager Barry Westwood said: "The controlled motorway system will greatly benefit drivers on these sections of motorway - helping to reduce congestion and make drivers' journeys safer and more reliable by smoothing traffic flows."
Mr Westwood said the system would have a "positive impact" on the surrounding area, as it reduced noise and air pollution from the road.
He added that the system which was already in operation on the M25 had seen an overall reduction in emissions of between 2% and 8%.
A 12-week consultation period for the proposals has now begun.