The three young victims were on a birthday outing

The �600,000 plan for Oxford's Eastern Bypass, which includes reducing the speed limit to 50mph, was agreed by the county council cabinet on Tuesday.

Josh Bartlett, Marshall Haynes and Liam Hastings died along with Howard Hillsdon, 21, in the crash.

The new barrier will prevent vehicles crossing the central reservation.

An Oxfordshire County Council spokesperson said: "No central barrier had been installed on this stretch of eastern bypass because, until very recently, there had been a very low record of accidents where vehicles had crossed the central reserve."

Celebrating birthday

Electric power cables running along the central reservation also added complications, he said, preventing the usual type of metal crash barrier being installed.

"However, the council has overcome this by proposing a vertical concrete safety barrier system that meets the need to prevent crossover accidents, as well as the needs of electricity companies."

Richard Dix, the county council's interim head of transport, said: "The cost of the particular type of barrier needed has meant this is a reasoned exception to the general rule on safety schemes, and not a precedent to set those rules aside."

The 13-year-old boys had been celebrating a friend's birthday when the Citroen they were in collided with Mr Hillsdon's Honda.

Last month, Mr Hillsdon's family held a fun day to raise money for a memorial bench and a plaque in the lifeguard's memory.