Angry horse riders threatened to put a spanner in the works of the dualling of the A11 after highways officials failed to add a road crossing to its provisional plans.

Angry horse riders threatened to put a spanner in the works of the dualling of the A11 after highways officials failed to add a road crossing to its provisional plans.

A series of public exhibitions on the upgrade of the road between Thetford and Barton Mills came to a close last week after the £127m scheme was brought forward by the government.

But a local access group and horse society said they would be lodging formal objections to the nine-mile dualling project unless the Highways Agency added a bridge or underpass to allow riders and cyclists to cross the A11.

The opposition from the British Horse Society and Federation of Suffolk Byways and Bridleways could force transport minister Geoff Hoon to call a public inquiry into the plans, which could hold up work on the last single carriageway link between Norwich and London.

Campaigners say the addition of a bridge or underpass, preferably near the Elveden war memorial, would help boost the area's equestrian tourist trade.

But a Highways Agency spokesman said that a crossing for “non-motorised users” had not been added to the A11 dualling plans because of the “very little usage” of local rights of way. However, officers were making arrangements to meet with objectors before a public consultation exercise ends on February 19, he said.

Work to address the missing link of the A11 is currently scheduled to begin at the end of 2010, but could start earlier if a public inquiry was not required.

Brian Freemantle, east of England welfare officer for the British Horse Society, said the Highways Agency was proposing an access bridge across the dualled A11, but at the moment it was only designated for farm traffic and pedestrians.

“We are not trying to blackmail them or hold this up. What we are asking for is some form of crossing for non motorised use. The approximate cost of a bridge would cost about £200,000 and this is a £127m project. A public inquiry would cost as much as it would for providing for the needs of everyone else,” he said.

Mr Freemantle added that the strength of feeling was such that some individuals - not supported by the horse society - were threatening to cause traffic chaos by riding their horses down the A11 in protest of the Highways Agency proposals.

Elizabeth Barrett, chairwoman of the Federation of Suffolk Byways and Bridleways, added that she had already lodged her formal objection to the Thetford to Barton Mills improvement works because of the lack of a crossing.

“I am getting in touch with local riders and they are horrified about what is happening and I will go to a public inquiry if necessary. We are classed as vulnerable road users and I will hold up the process if we do not get a crossing. Horse riding is a healthy outdoor recreation and I know a lot of riders in the area that would certainly use it,” she said.