Police declined to say how many staff would be working but Dunedin and Clutha area commander Inspector Dave Campbell warned, "This would not be a good weekend for anyone to break the law."
Police tactics will include highway patrols from Christchurch to Dunedin, checkpoints, hotel visits, policing liquor bans and having multiple officers on foot and in patrol cars in the North Dunedin area from 6pm Friday.
Insp Campbell said there was "no shortage of volunteers" for the weekend's "Operation Undie 500", including highway patrol, traffic, tactical, team and uniformed police staff.
Police did not expect as many people to travel south as for last year's event, but were prepared for any eventuality.
The annual Undie 500, in which students drive from Christchurch to Dunedin in vehicles costing less than $500, would have marked its 20th anniversary this year.
The event was marred by disorder in 2006 and again last year.
Attempts to negotiate a revamped Undie 500 with authorities failed and traditional organiser Ensoc (University of Canterbury's engineering society) cancelled the Undie 500 this year.
Legal advice also led to the cancellation of an alternative official event, Trek 08.
A rogue event has been talked about on social networking websites Facebook and Bebo since the official events were cancelled and an email was circulated among Canterbury University students this week saying an Undie 500-style rally was planned for this weekend.
Ensoc president Graeme Walker and University of Canterbury Student Association president Michael Goldstein yesterday moved to distance themselves from the email.
Mr Goldstein emailed all Canterbury University students to reiterate that the Undie 500 was off and warned those considering heading south they must take responsibility for themselves.
Mr Walker had heard some people were heading south, but did not know how many or who they were.
Members of Ensoc will travel to Dunedin for the Marlowe Cup, a traditional rugby match against the Otago University Surveying Students Association, this Saturday.
The match had been held in Dunedin every second year since 1955, and it was a coincidence the game fell this weekend, he said.
Insp Campbell said a liquor ban from 7pm on Friday to 7am on Monday was in place for North Dunedin's student area.
University of Otago Students Association president Simon Wilson said there was little else to do but "wait and see" what happened.
OUSA had advocated for a controlled event and he understood Dunedin authorities' reasons for saying no to the rally, but the result was no-one knew what to expect.
" I hope . . . not many people come down."
