Six months' of security preparations will try to ensure the safety of May morning revellers who traditionally gather on Oxford's Magdalen Bridge.
It is tradition to jump from Magdalen Bridge on May Morning
Last year, at least four people jumped into the River Cherwell after climbing over a two-metre security fence.
More than 8,000 people had gathered on and around the bridge to hear choristers sing hymns at dawn from the tower at Magdalen College.
Safety measures include police supervision and an alcohol amnesty.
Between 1998 and 2000, the bridge was closed during the celebrations to stop people jumping in the river, and over concerns about the parapets, which have now been strengthened.
This year, stewards will be working to deter people from jumping into the river and there will be restricted access and barriers.
The site is in the city's alcohol-free zone but if revellers dispose of any alcohol into bins they will not be prosecuted under the amnesty.
Chief Inspector Chris Parker-Towle said: "The police are there on May morning for public safety reasons, not because of the alcohol-free zone.
"It is part of Oxford's history and usually passes without any trouble.
Appeal not to jump
"The tragic event of a person being paralysed after jumping from the bridge is still fresh in our minds and we are all working together to ensure that sensible safety precautions are in place for the celebrations."
Oxford City Councillor Susan Brown said: "We know how important this day is for people in Oxford.
"That's why the city council, with the police, has been again working hard for the last six months to prepare for the celebrations and ensure people welcome in May morning safely.
"I would also like to appeal to anyone thinking of jumping off the bridge to not do this. "