Police in Dunedin say the behaviour of crowds associated with an unofficial "Undie 500" at the weekend, was a vast improvement on previous years.
Dozens of police in riot gear formed skirmish lines to disperse about 300 people gathered on Castle Street in earlyon Sunday.
Inspector Lane Todd says they responded after a small fire was lit on the street.
He says bottles and rocks were thrown at the police as the crowd was forced back, although far fewer than in previous years.
Altogether, 30 people were arrested. Charges include obstruction and disorderly behaviour.
Last year's event ended in riots and 70 arrests. The Polytechnic Students' Association says the disorder damaged the reputation of all Dunedin students.