Its advice comes after the A12 Inquiry, launched by Essex County Council, recommended that the government restore the route to ‘national’ strategic road status.
The inquiry highlighted the fact that the A12 is under significant stress, a situation that is likely to worsen with the new housing and ports planned for Essex.
An upgrading of the route to modern dual two-lane standards – with HGV overtaking bans, speed limits and better quality lay-bys – is the way to ease congestion, according to the council’s report.
David Holmes, chairman of the RAC Foundation, welcomed the inquiry’s work but stressed that there are "many national roads" that need attention and action and urged Ms Kelly to review the many other non-motorway roads.
He said: "The report shows that the department’s policy of abandoning responsibility of roads that are not motorways to regional bodies is no way to address the serious congestion and safety problems that these roads present."