A concrete crash barrier in the central reservation of a notorious stretch of Oxford's Eastern By-pass will be built with gaps to accommodate two ancient rights of way crossing the road.

Rights of way are protected from closure by law.

But today, Oxford East MP Andrew Smith MP, who campaigned for the barrier to be built after three boys and a man were killed in May in a 'crossover' crash, said enabling pedestrians to cross the road was "an accident waiting to happen" and called for a footbridge to be built.

Mr Smith said: "This is something that should have been sorted out long ago. Rights of way are important, but to enable people to cross a bypass is an accident waiting to happen.

"What I would call for is the application of some common sense. It's an incredibly dangerous stretch of road and it surprises me the Highways Authority, in the knowledge there is a right of way, doesn't have some duty of care towards the people using it. The answer is a foot- bridge."

Oxfordshire County Council assistant head of transport Richard Dix said: "The county council, along with every single highway authority in the land, is obliged to recognise rights of way crossings over A-roads.

"The council's compliance with this law does not mean it is actively encouraging people to cross a dual carriageway. Indeed, there is so little possibility of people wanting to cross the bypass there is no economic case for spending £300,000 on a bridge crossing.

"If this situation is to change it would have to be changed at national level."

County councillor and cabinet member for transport David Robertson added: "If there was some way I could shut off the rights of way I would. I regret the fact, but we're not to blame and we're certainly not encouraging people to cross the road."

Construction work on the £600,000 barrier is due to start next week. It will have the gaps at Kiln Lane, near Shotover Country Park, and Horspath Driftway, near Brasenose Wood.

Oxfordshire County Council highways engineers originally opposed the idea of a barrier because of the small number of crossover crashes.

Many motorists wrote to the Oxford Mail, saying a crash barrier was unnecessary, but the county council eventually bowed to the pressure of a campaign.

As part of a package of safety improvements, the entire stretch of the Eastern Bypass is to be made a 50mph zone, with police told to conduct regular speed checks.

Sam Hastings, the mother of Liam Hastings, one of the boys killed in the accident in May, added: "It's fantastic they are going to build a crash barrier, but that's not going to bring Liam back. I wouldn't cross a busy bypass."