"He was a drunk driver coming back from the beach," he said.
"We're going to be here for the express purpose of catching people drinking at the beach and returning."
He said they were "very concerned" about keeping Masterton-Castlepoint Rd safe for drivers.
"It's our number one focus at the moment, and it's something we can put a lot of pressure on."
He said they would like to spend more time with breath testing on SH2 but it was a big area to cover.
"Whereas here, this the only way in or out."
The state highway was not neglected, with the Times-Age spotting several police vehicles on New Year's Day traffic duties between Featherston and Masterton that morning.