State transportation officials said last week that when Transportation Secretary Stephanie Pollack said this week that highway carpools lanes are mostly filled with scofflaws she wasn’t basing it on any hard evidence.

Speaking to local officials on Tuesday about high-occupancy vehicle lanes, Pollack said that transportation officials “think as much as 80 or 90 percent of the traffic is actually just individual people in cars.”

MassDOT wants to look into opening more HOV lanes to ease congestion, she said, but first has to “figure out a way that they’re actually high-occupancy vehicles and not just individuals who are brazen enough to use the lane.” A recent report from the Baker administration also suggested using tolled HOV-type lanes to help deal with Boston traffic, an idea which drew skepticism from many transit advocates.

A 2017 study from an arm of the Boston Region Metropolitan Planning Organization found about 18 percent of HOV lane cars have only the driver inside, the Boston Globe reported on Friday.

A MassDOT official said Pollack was making an anecdotal reference to the HOV lane on Interstate 93 through Somerville and Medford. The other HOV lane in Greater Boston, on the Southeast Expressway, is thought to function more effectively, the official said.

At the Local Government Advisory Commission meeting Tuesday, Pollack told local officials that repeat HOV lane scofflaws use social media to alert each other when the supposed carpool lanes are not being monitored.

“I was shocked to find out that there is a closed Twitter group for people who use your carpool lane where they tweet at each other and say, ‘there’s no cops, it’s OK for single cars to use it,’ ” she said.