Who were those people on Santa Rosa’s pedestrian overcrossing?

Those people on a Highway 101 pedestrian overpass in Santa Rosa staring at traffic for hours have stoked curiosity, and at least one complaint from a passing driver.

Wearing hard hats, bright safety vests and even a gas mask in one case, they sit or stand, almost statue-like, intently watching vehicles.

It’s not a political demonstration, street theater, or some strange cult. Over the past two days, they were engaged in a Bay Area transportation survey, counting occupants in each vehicle.

It’s part of the Metropolitan Transportation Commission’s “Managed Lanes Implementation Plan,” according to Ross Hughes, a supervisor for Metro Traffic Data, the company hired to count the number of vehicle occupants during peak commute hours.

Using computer pads, the dozen or so workers “attempt to count how many people are within each car, within each lane,” he said.

The data, he said, will go to engineers who are monitoring freeways and high occupancy lanes all over the Bay Area in an effort to reduce congestion.

Hughes said the data may be used as a basis to convert some lanes to paid express lanes, where single occupant vehicles could use lanes currently reserved for car pools.

“It’s a less expensive way to reduce congestion without adding infrastructure,” he said.

Metro Traffic Data workers were completing their two-day survey Thursday evening on a pedestrian overpass just south of Highway 12 that connects South A street on the east side, to South Davis Street on the west.

The southbound traffic near Santa Rosa’s busy freeway interchange was at its usual crawl as motorists passed under the watchful gaze of the workers overhead.

“We get flipped off a lot. We get honks, waves, thumbs up, thumbs down,” he said over the din of traffic. “Some people are upset the government is watching them.”

Hughes said Santa Rosa Police came by because one motorist complained they were “being intimidated by someone up there.”

“We’re doing our best to not engage the drivers, although we’re pretty conspicuous,” he said. “We don’t need people rubber-necking or causing accidents.”

You can reach Staff Writer Clark Mason at 521-5214 or clark.mason@pressdemocrat.com. On Twitter @clarkmas.