Three Court of Appeal judges upheld the original decisions by the Transport Secretary to grant development consent back in August 2022.
The legal action has delayed the trio of dualling projects by 20 months, raising taxpayer costs by tens of millions of pounds.
While environment campaigners could still take their case to the Supreme Court, National Highways confirmed it now planned to work with its contractors to establish new timescales, including the start of major construction, for all three projects.
This will be announced over the coming weeks.
Three road improvement schemes
Dualling A47 between Blofield – North Burlingham
(Cost £90m-£100m, Galliford Try)
Dual carriageway and junctions on the A47 between North Tuddenham – Easton
(cost up to £200m, Galliford Try)
Redevelopment of Thickthorn junction – where A47 meets the A11 south of Norwich
(Cost up to £100m, (project rebid for better value) Contractor to be confirmed
Chris Griffin, Programme Leader for National Highways in the East Region, said: “I am very pleased the Court of Appeal has decided that the DCOs for these schemes were valid.
“This outcome potentially puts us one step closer from progressing these important road improvement projects unhindered by further delay.
“The A47 is a vital artery connecting the east of the country with the heart of UK. Being in a position to move forward with our job of delivering a safer and more reliable road that will contribute towards long-term economic growth for the region and help to connect people and communities is very exciting.”