Car pools and commuter buses are a bit more common along a stretch of Interstate 66 after some drivers began paying tolls two years ago during peak commuting hours, according to a new report.

The Northern Virginia Transportation Commission conducted the study to determine whether mass transit ridership and commuter behaviors have changed along the 10 miles of I-66 inside the Beltway. The report showed fewer vehicles are using I-66 during the morning rush, but more people are moving through the corridor.

The agency receives some of the toll revenue collected along the corridor, then uses that money — about $15 million to $20 million annually — to support transit options in the region. The report’s findings were presented Thursday to the commission’s board.

“We were pleasantly surprised,” said Kate Mattice, executive director of the commission, which coordinates transit and other transportation projects in Northern Virginia. “This data represents two years of funding, and we can see that we were able to grow the commuter bus usage to move people through the corridor.”

The analysis looked at traffic counts and bus ridership from Northern Virginia commuter bus services. Researchers looked at data from 2015 — two years before tolls were put in place — through last year.

According to the report, about 60,000 people and 27,000 vehicles travel inbound each weekday along the I-66 corridor between 6:30 a.m. and 9:30 a.m. The study found an average of 750 fewer vehicles traveled through the I-66 corridor each weekday morning, alongside an increase of about 700 people, when compared with 2015.

The corridor saw a slight increase in the number of people using mass transit and riding with other commuters, the report showed.

Car pools and van pools consisted of 23.7 percent of vehicles moving through the corridor during the morning rush last year, up from 22.5 percent in 2015. The percentage of vehicles occupied by motorists driving alone fell from 36.4 percent in 2015 to 34.7 percent last year.

Toll rates have been sharply criticized by some state and local politicians, as well as commuters, who say tolls that occasionally surpass $45 during the peak of the morning commute are excessive. State transportation officials counter that such high tolls aren’t the norm and are paid by relatively few drivers.

The tolls are in effect weekdays from 5:30 a.m. to 9:30 a.m. in the eastbound lanes and from 3 p.m. to 7 p.m. westbound. There is no cap on the price, which increases as congestion rises. Drivers must pay if they are alone, but usage is free with two or more people in a vehicle equipped with an E-ZPass Flex transponder.

When the tolls inside the Beltway were approved, Virginia transportation planners said they hoped the cost would encourage commuters to carpool or use public transportation during peak travel times. Mattice said the report shows some motorists have changed how they commute through the region.

Officials have also added more than 50 commuter bus routes in the region since tolling began in December 2017. Commuter bus lines in the region, including OmniRide, Loudoun County Transit and the Fairfax Connector, saw a 26 percent jump in ridership since 2015, the report said.

“We’re seeing more people on buses, so they’re off I-66,” Mattice said. “That frees up the road so those who do need to drive have a less crowded roadway, and they have a chance for less expensive rides.”

Critics of the I-66 tolls say they’re not convinced the tolls are worth it.

Ron Meyer, a former Loudoun County supervisor, said the report’s findings show only slight changes in commuter behavior when considering the costs passed along to drivers. Meyer, who now advises businesses on public-private partnerships in transportation, said the study shows tolling “isn’t a great way to incentivize people into transit.” Meyer served on the NVTC’s board from 2016 to 2019.

“We’re trying to grow our economy and improve people’s quality of life,” he said. “You’re raising their cost of living with tolls, and that’s overall not a net improvement to folks in the corridor.”

Virginia Del. Danica A. Roem (D-Prince William) said that although she opposes the tolls, new commuter lots in western Prince William County have helped to encourage people to take commuter buses into the District. She said commuters need improved infrastructure and alternatives to paying tolls.

“Tolls should never have been put in place,” she said. “I’m not happy that any one of my constituents are priced out because they live in, say, Manassas Park and not McLean.”

The study did not look at the effect tolling has had on adjacent roadways that offer toll-free alternatives for motorists.

A Washington Post analysis one year after the 66 Express Lanes opened found the new tolling system shifted the times when some motorists traveled. That analysis showed that as drivers avoided peak hours and the accompanying tolls, it created traffic backups at times when the lanes were free.

Outside the Beltway, crews are adding 22.5 miles of toll lanes starting in Gainesville, in Prince William County. Motorists will be able to choose between the general lanes, which will remain free, or the new high-occupancy toll (HOT) lanes, which buses, carpoolers and motorcyclists can use free.

State officials say the project, expected to be completed in 2022, will relieve congestion along the entire I-66 corridor near Washington.

Read more: