Widening of the A21 approved
Part of the A21 which links London, Kent and East Sussex will be turned into a dual carriageway, the Highways Agency has announced.
The decision follows a public inquiry in May 2013, the agency said.
The 2.5-mile (4km) section of the A21 between Tonbridge and Pembury will be upgraded from a single to a dual carriageway.
"The major road scheme will make journeys on the A21 safer and more reliable," the agency said.
Graham Link, Highways Agency project manager, said: "The A21 is a vital route linking the Tonbridge/Tunbridge Wells and Hastings/Bexhill areas to the M25 and London.
"The new section will provide much-needed capacity to reduce congestion and will also improve safety with new junctions provided and a better road layout."
Some work is expected to begin in autumn, with the main building work due to begin in spring 2015.
Greg Clark, Conservative MP for Tunbridge Wells said: "This is the news that everyone has been waiting for.
"This stretch of road is notorious across the South East for its tailbacks, as well as being one of the worst accident blackspots in the country."
He had previously described parts of the A21 as being "little better than a country lane".