Angry council leaders and business bosses have accused highways chiefs of "completely wasting" five years, when progress could have been made on £300m of improvements to the A47.
While the improvements, including changes to Thickthorn roundabout on the edge of Norwich and dualling of sections between North Tuddenham and Easton, plus Blofield to North Burlingham, were agreed in 2014, work has yet to start.
And, at a meeting of the A47 Alliance - made up of business leaders, councils and stakeholders along the road's route - frustrations boiled over.
Nova Fairbank, chief operating officer of Norfolk Chambers of Commerce, said: "We are the breadbasket of the UK and have huge opportunities from offshore renewables, so we have to see our region given much higher priority.
"But we are always the also-rans. When you consider our road system is 50 years behind anywhere else in the UK it's not good enough."
Matt Stafford, divisional director at National Highways - which is responsible for getting the work on the A47 done - said that 18 months ago, there had been a "reset" over what was happening with progress on the A47 schemes.
Since then, development consent orders have been lodged for three Norfolk schemes.
And Mr Stafford said: "We are absolutely on track with what we are committed to doing. We are very focused on that.
"I acknowledge and hear what you say about what has happened previously. I can change what happens in the future."
But Graham Plant, deputy leader of Norfolk County Council, reacted angrily to the news of that "reset".
He said: "So, five years were completely wasted, to reset 18 months ago, to get where we are today? That is really disappointing and says a lot about your company.
"You are holding up the building of roads and the infrastructure we need for this county."
Mr Plant went on to criticise National Highways for the absence of Norfolk schemes, such as the dualling of the Acle Straight, in future road investment strategies.
Mr Stafford said he did not "buy into" all of Mr Plant's narrative and said it was the Department for Transport, not National Highways, which decides which schemes are included.
The A47 Alliance is still pushing for the full dualling of the road, which stretches from Lowestoft to Peterborough, with Norfolk County Council having reignited the Just Dual It! campaign.
Council leaders are hoping the government will make money for the A47 available in its comprehensive spending assessment next month.
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