Mayor of Cambridgeshire and Peterborough James Palmer attended his first meeting of the A47 Alliance and the Just Dual It! campaign to join the calls for the Government to fully dual the road between Peterborough and Lowestoft.
Mr Palmer was at County Hall in Norwich last Friday for the meeting.
Highways England has committed to dualling some stretches of the A47 but this will still leave substantial sections as single carriageway.
Mr Palmer said: “It frankly beggars belief that in the 21st century this essential trunk road which joins two major urban areas in Norwich and Peterborough is single carriageway for the majority of the route.
“I felt the Highways England proposals already on the table – the dualling of 2.5km of road from Wansford to Sutton and improvements at the Guyhirn roundabout by 2021 – were not nearly ambitious enough.