Nelson police stopped 1000 vehicles at checkpoints in a weekend operation targeting people pre-loading before heading into the city's bars.
Five people were picked up with excess breath alcohol and police issued 100 infringement notices at checkpoints on Nelson's main arterial routes, Waimea Rd and Rocks Rd.
Senior Sergeant Grant Andrews said the vast majority of people stopped were compliant and gave positive feedback about the police presence.
''People expect to see us out and stopping drivers early in the evening is a very effective way of preventing issues or crashes later in the night,'' he said.
However, he said police were disappointed with the speeds some drivers were clocked at on the open road over the course of the weekend, with several exceeding 130 kmh.
In the lead up to Christmas police would continue to be highly visible on the roads and around the city's bars and clubs, he said.