Vining said four drivers elsewhere in Gisborne returned breath alcohol readings above the legal limit and were to appear in court.
On Saturday, about 440 drivers were tested near the showgrounds.
“No alcohol or drugs were detected with those drivers,” he said.
“However, elsewhere in Gisborne, a further 500 drivers were tested, with four receiving infringements and four drivers summoned to appear in court.”
Vining said motorists should not drive when impaired by alcohol or drugs.
“This highlights the ongoing need for public awareness and responsible decision-making.
“We urge all road users to plan ahead, avoid driving under the influence, and to speak up if they see unsafe behaviour.
“The goal is to prevent harm and ensure everyone gets home safely,” he said.
“We encourage anyone who sees unsafe driving behaviour on the road to contact us as soon as possible.”
The public were advised to call police, either via 111 if the concerning behaviour was happening currently or to make a report through 105 if it was being reported afterwards.