Work to reduce congestion on a key link between London and Brighton will start later this year, it has been confirmed.
The Highways Agency said initial work on the A23 road-widening scheme between Handcross and Warninglid would begin in October.
The scheme for a three-lane carriageway in each direction will cost between £76m and £105m.
The agency said improving transport infrastructure would help the economy to recover.
'Vital for economy'
Plans to improve the A23 in a bid to improve journey time and safety were approved by the government in March 2010.
The project was among a number of major schemes safeguarded in the government's Spending Review last October.
Full construction will start next April and is set to last two years.
The agency said a 40mph (64km/h) speed limit would be in place while work is carried out.
Paul Arnolds, a senior project manager at the Highways Agency, said: "It's important for the 65,000 people that use the road every day.
"Transport infrastructure is vital for the economy. It has to be seen as helping the economy to recover."