Drivers would have to shell out more to travel solo and some car poolers would have to add another rider during peak commute times under a Metropolitan Transit Authority plan to keep traffic speeds up on its high-occupancy toll lanes along area highways.

Solo drivers paying to use the lanes could see tolls rise to as much as $8 on some segments during peak travel periods.

“We have to take a tougher approach, and this is a tough approach,” Metro board member Jim Robinson said.

The Metro board of directors is scheduled to consider the rule and price changes Thursday. If approved, the changes would take effect June 1.

The transit agency oversees the lanes along Interstate 45, Interstate 69 and U.S. 290, that were built more than three decades ago with federal money intended to aid commuter buses and reduce congestion. Metro converted them from high-occupancy vehicle lanes to high-occupancy toll lanes in 2012.

In opening them to toll-paying solo drivers, however, Metro said the lanes must maintain an average speed of 45 mph. As congestion around the region grows, greater use of the HOT lanes is dropping speeds toward that 45 mph average and far slower during peak commute times.

“We are falling to 10-15 mph lanes or a rolling parking lot,” Robinson said.

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Recent attempts to fix the problem, including increased enforcement of car-pool rules and joining the Tow & Go program for clearing stalled cars from the roadway more quickly, have not worked, Metro CEO Tom Lambert said.

Metro officials now hope the toll hikes and stricter carpool and vanpool requirements will do the trick.

The proposed changes would apply to four of the five segments of HOT lanes, the lone exception being I-69 north of downtown, where traffic speeds remain above the 45 mph threshold. On the four remaining routes, the lanes will be open only to car pools, commuter buses and van pools from 6:30 to 8 a.m. and from 4:30 to 6 p.m.

Further, car pools would need at least three occupants from 7 to 8 a.m. and between 4 and 6 p.m. All other times, HOV users will need only two occupants in the vehicle.

Solo drivers, meanwhile, will pay more no matter when they travel. From 5 to 6 a.m., solo drivers will pay $2.50, an increase of 25 cents. In the 30 minutes before HOV-only use starts, tolls will increase to $8 on every lane except I-69 north. In some cases, that would be a $3.50 hike.

“This is not a revenue stream for Metro,” Lambert said as board members discussed the staff proposal last week.

Rather, officials said, the price increase is meant to motivate drivers to consider car pools, van pools and commuter buses or change their driving habits.

“You are telling to toll payers, ‘Y’all need to move out of the way’ and encourage them to move their trip 30 minutes,” Metro board member Lisa Castañeda said.

Castañeda, deputy director of the Harris County Toll Road Authority, said that while she understands many will complain, the price hike can be approached as a way to lower costs if a driver who already is willing to pay $5 leaves earlier when tolls are $2.50.

“I know it is going to impact people, and I don’t mean to downplay that, but it is 30 minutes,” Castañeda said. “If I change my hours, I will go down to $2.50.”

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Drivers, while sympathetic to the problem of slowing speeds on the toll lanes, said they wanted Metro to do more to catch offenders, some insisting that was the source of much of the slowdown.

“Every day I see someone in the car pool lane who should not be there,” said Richard Thomas, 51, who commutes daily with a coworker from Spring. “If I see it every day, why aren’t they out there catching them every day?”

Metro Police increased enforcement in January and nabbed 1,074 violators along the toll lanes, nearly 500 of those along I-45 north of downtown. The stepped-up policing, however, did little to speed up the lanes, officials said.

“We can’t get it done with that,” Lambert said.

In Metro’s hierarchy of whom it is trying to serve with the HOT lanes, commuter buses and van pools take precedence, officials said, even if that means toll payers are deprived.

“We are not in the toll road business, we are in the mass transit business,” Robinson said. “Really, our goal is to get those people on park-and-ride buses.”

As the changes are contemplated, Metro also is making plans for major upgrades and changes to its commuter bus service. After redesigning its local bus network in 2015 and securing voter approval for $7.5 billion in new projects, transit officials next month are set to consider changes to the park-and-ride system. Among those changes would be more connections between suburban job centers and more direct service to and from downtown.

Those changes precede attempts, as part of the Metro Moving Forward long-range plan, to add two-way HOV or HOT lanes along area highways. That two-way service dramatically improves travel times, officials said, by allowing commuter buses to avoid traffic in both directions.

Even with investment that could take years to build, Lambert said, he expects those car pools and solo drivers to be squeezed even further in favor of more buses and vans. That will mean Metro is likely to re-evaluate its prices and rules more regularly, he said, such as once or twice a year.

“We need to be having a conversation not about how to get to that minimum speed, but the maximum use,” Lambert said.

dug.begley@chron.com