WORK to widen the A12 is due to start within three years and will 'connect people across the county'.
The scheme is part of a £1.1billion investment in East of England roads which will begin before 2020.
As part of the plans, the dual-carriageway is set to be widened between its junction with the A120, at Marks Tey, and Chelmsford.
A consultation on the plans is set to be launched by Highways England on Monday, January 23.
Witham Mayor, Patrick Horner, said he was surprised to hear the work will come before A120 improvements.
He said: "Transport companies are ever so worried about what end they are starting from, there could be a huge amount of re-organisation.
"This is going to be massive and it will be interesting to see what line they choose.
"They have got lots of things to consider that we don't think of, for example all the junctions have to have certain gaps between them.
"It's major and an awful lot of money, usually they require about 10 years for a major project."
Tina Townsend, chairman of the Witham Chamber of Commerce, thought it would be a good opportunity for people to access jobs in the town.
She said: "This is great news for Witham and will hopefully bring more businesses to the town and improve access for those already here.
"We look forward to seeing the plans."
The A12 scheme, which will be completed alongside improvements in Suffolk, Norfolk and Cambridgeshire, was initially announced in December 2014.
Witham MP Priti Patel has welcomed the announcement.
She said: "The A12 is a major economic corridor connecting people and businesses across the county.
"Widening the road through the Witham constituency will reduce congestion, improve safety and increase economic growth.
"By improving connectivity across the county we can open up new business and employment opportunities that boost our economy.
"I have been campaigning for improvements to the A12 since being elected and am pleased to see the progress being made with making this a reality.”
Transport Secretary Chris Grayling said: “The Government is making a record investment to improve our motorways and major ‘A’ roads across the country to get motorists to their destinations more quickly, easily and safely.
“These vital schemes in the East of England will not only help relieve congestion, they will also link people with jobs and businesses with customers, helping boost the region’s economy and improving lives.”
Jim O’Sullivan, chief executive of Highways England, said the improvements are made possible by the Government’s £15 billion investment.
He said: "They are much needed by the half a million drivers who use them every day.
"Each scheme has been developed by working with local partners and through this consultation we are welcoming views on them.
"I encourage anyone with an interest in these roads – whether they drive on them, live near them or depend on them for trade – to get involved.”