Utah Highway Patrol Trooper Jeff Kinghorn drove near the SUV zipping along the car-pool lane on Interstate 15 in Bountiful on Friday to see if the driver had a required passenger or a toll transponder. He lacked both.

As the driver saw the trooper eying him, he compounded problems by crossing over the double-white lines to get out of the express lane, another violation. Kinghorn then noticed the SUV’s license plates had expired.

So the driver hit a trifecta for potentially expensive violations. The penalty for using the car-pool lane illegally or crossing the double-white line is up to $337 for each.

“He said he knew he was in violation of express lane rules but was just cruising there” — at 10:15 a.m. when little traffic was in the other lanes anyway, Kinghorn said. It’s a bad habit that too many Utahns apparently have developed.

(Rick Egan | The Salt Lake Tribune) Utah Highway Patrol Trooper Jeff Kinghorn, prepares to pull over a vehicle for an HOV violation on I-15, Thursday, Nov. 1, 2018.

The Utah Department of Transportation estimates that a quarter to a third of all vehicles now using car-pool lanes are there in violation of rules — up from about one of every five in studies a few years ago.

So UDOT is funding quarterly blitzes of overtime shifts for Highway Patrol troopers, including one now, to reduce the problem.

Kinghorn didn’t need to look hard Friday for violators, even during the light traffic of a late morning in Davis County. Three minutes after his first catch drove off, he caught another one.

That SUV crossed the double-white lines halfway into the car-pool lane, then crossed back, perhaps as the driver saw the trooper. She sped up aggressively on the bumper of another car and made more dangerous lane shifts. And her license plate had expired, too.

Another trifecta.

“She said she was late for an appointment,” Kinghorn said. “Most of the express lane violations we see are in the morning and afternoon commute times, when people are in a hurry.” But his catches show they do happen all day.

(Rick Egan | The Salt Lake Tribune) Utah Highway Patrol Trooper Jeff Kinghorn, monitors talks to a driver, after noticing a violation in the HOV lanes on I-15, Thursday, Nov. 1, 2018.

UDOT and the Highway Patrol invited news media for ride-alongs Friday to urge compliance with car-pool-lane rules — saying violations are increasing and dangerous and deadly.

“In rush hour, many people try to jump in and out of the express lanes by crossing the double-white lines," said Highway Patrol Corp. Greg Hollingsworth. “That’s a real problem because people in the express lanes often aren’t expecting it, and are traveling significantly faster than the other lanes. It causes accidents.”

UDOT spokesman John Gleason said problems have especially appeared in long stretches of car-pool lanes in Salt Lake and Utah counties where, because of construction, the agency suspended normal requirements to have at least two people in the car, and waived tolls for single-driver cars, with or without a transponder.

Despite that, it is still illegal to cross the double-white lines. He said many people are ignoring that — and many drivers don’t expect it.

Gleason said that relaxing toll and passenger rules in those construction zones may have led more people to violate rules elsewhere. UDOT says it also is noticing that as growth and congestion increase, so do car-pool-lane violations.

The Highway Patrol is often too busy with accidents and other serious problems to focus on car-pool-lane violations — which is why UDOT funds overtime for occasional blitzes.

“The car-pool lanes are getting clogged with people who don’t belong there," Gleason said. “We’re asking people to help us and obey the rules.”

When used properly, he said, express lanes move twice as many people as general-purpose lanes — 3,630 people an hour compared to 1,980. That also helps reduce congestion in other lanes.

To encourage car pooling, UDOT aims to keep speeds in the car-pool lanes at least an average of 55 mph, and federal law requires maintaining average speeds of 45 mph or some state funds could be threatened. But average speeds have been dropping — to as low as 31 mph in some congested stretches during the afternoon peak commute.

To take advantage of excess space in car-pool lanes, UDOT for years has sold electronic toll transponders to allow some single-car drivers to use the lanes. But because of peak-time congestion, it recently doubled maximum tolls to $2 per 10-mile section, up from $1. It has permission from the Legislature to raise them higher if needed.

“So far, it seems like the higher tolls have helped improve overall speeds during peak times,” but more study is still needed, Gleason said. “And it would help if we could reduce the number of people who violate rules to drive there."