Police in Dunedin are preparing for the annual Undie 500 car rally this weekend, with about 90 vehicles expected to arrive on Friday night.
About 600 Canterbury students will travel from Christchurch to Dunedin in a motorised pub crawl in vehicles worth less than $500.
For the past three years, there has been disorder in north Dunedin the day after the rally, with riot police called in to disperse the crowd in 2007.
Cars were torched, dozens of street fires were set alight and police and firefighters were pelted with bottles. There were 69 arrests and the incident led to the cancellation of the event last year.
However, an unofficial rally went ahead regardless and disorder ensued.
Inspector Dave Campbell says extra officers have been rostered on this weekend and a liquor ban is in place. Diversion will not be offered to anyone arrested.
Dunedin Mayor Peter Chin says the event is the catalyst for reckless behaviour. He hopes this year will be different, but is not confident that will be the case.