A Toast Martinborough festival-goer was hit by a bus and seriously injured in what marked a sad end to a damp but successful day among the vines.

The woman, aged in her 20s, suffered serious head injuries when she "walked out in front" of the bus near Palliser Estate at 7pm yesterday, police say.

The accident was witnessed by many festival-goers, who were left shaken as they prepared to leave the festival.

The route was closed to all traffic, and buses were diverted through Ponatahi.

The woman was driven by ambulance to Greytown, then flown to Wellington Hospital.

It was an unfortunate end to the 21st edition of Toast, which has been held in Wairarapa since 1992.

Police, organisers and punters all praised yesterday's event as a success, with instances of drunkenness and aggressive behaviour rare.

Senior Sergeant Carolyn Watson, officer in charge of the event, said eight people were arrested for disorderly behaviour or minor assaults, mainly in the final hour of the event between 5pm and 6pm.

Six others were taken to sober up in a tent run by St John.

One man was arrested after getting behind the wheel of an ambulance after it had pulled up beside him to help a patient.

Officers "hauled out" the "extremely intoxicated" man and he was later taken to the detox tent, Ms Watson said.

The high number of arrests - compared with just one last year - was because of higher numbers of police than previous years, and a joint initiative with organisers to target problem punters.

"We wanted to front-foot it this year . . . so we saturated the area with police and security and tried to remove people before they could get started," she said.

"The [number of arrests] were a little bit disappointing but it's a small minority of people, and I would expect more arrests due to more police, more visibility and a zero-tolerance stance."

A "howling southerly and pouring rain" meant most punters stayed in The Square or went to nearby pubs until after midday, she said.

Last year's event was criticised as the worst in seven years by the previous officer in charge, who warned that police might need to consider carrying batons to combat unruly drunks.

This year those arriving by train were greeted by a line of security guards who checked bags and poured out bottles.

The guards were also conducting visual alcohol checks for signs of preloading.

Cheaper and more substantial food was made available to drinkers, and pubs had to close by 1pm.

Toast general manager, Rachael Fletcher, said the event was a "resounding success" for the 10,000 visitors.

- © Fairfax NZ News