Plans to dual two single-lane bottlenecks on the main road between London and Hastings will not face further delays, it has been announced.
MPs say road widening is vital to coastal regeneration
A recommendation that work to widen the A21 between Tonbridge and Pembury and Kippings Cross and Lamberhurst be reviewed has been overturned.
Conservative MP for Tunbridge Wells, Greg Clark, said he was relieved the scheme would not be delayed.
He said work on the project in Kent was set to begin in 2010/2011.
Much of the A21, which passes through Kent and Sussex, is single carriageway.
Mr Clark said: "To delay the improvements once again [would] have heaped misery on local people who continue to be frustrated by congestion on the A21.
"We have already waited far too long for the road to be dualled. We have had ministerial commitment that it will be done and it is essential that we now just get on with it."
He added: "More delay would mean more cost and potentially threaten the schemes from ever happening."
The South East England Regional Transport Board overturned the recommendation for a further review of the dualling work at a meeting on Wednesday afternoon.
Mr Clark and four other Kent and Sussex MPs had issued a joint letter stating that the road was vital to coastal regeneration around Hastings.