Proposed upgrades to a major road linking the East to the Midlands are "desperately needed", the Road Haulage Association (RHA) has said.
Improvements to the A47, which runs from Great Yarmouth to Peterborough and Leicester, were given the prime minister's backing.
John Howles, of the RHA in the East, welcomed the proposals and said the economy would suffer without the work.
But Labour dismissed the scheme as a pre-election gimmick.
A Labour spokesman said the proposal was short on detail and claimed there was no new money available.
David Cameron pledged upgrades for the A47 as part of a package of road schemes which he called "the biggest, boldest and most far-reaching road improvement programme in four decades".
The exact details of the A47 improvements have yet to be finalised. but possible features include making single carriageway stretches near Great Yarmouth, King's Lynn and at Thorney, near Peterborough, into dual carriageways.
Mr Howles said: "Improvements to the A47 are desperately needed. In the East of England we have only one decent road - the A14. The A47 is badly in need of an upgrade. Without it we see industry suffering."
He called on other political parties to also back the A47 upgrade.
Conservative MP for Great Yarmouth Brandon Lewis said: "The last government downgraded the road so to be back on the list with a promise of funding in the near future in such a short period of time is better than we could have ever hoped for."