Bus lanes are speeding up commutes in Greater Boston, according to newly compiled MBTA data.

Several Boston-area communities have tested out bus-only lanes in recent years, including Arlington, Cambridge, Watertown and Everett. These bus lanes have made buses faster and more reliable, according to BostonBRT, an initiative focused on developing bus rapid transit in the region. BostonBRT is backed by the Barr Foundation, which funded the pilots.

According to BostonBRT, commutes in Arlington shrank by up to 10 minutes because of the dedicated bus lane on Mass. Ave., while riders along the Cambridge-Watertown bus lane on Mt. Auburn Street saved about five minutes on average. BostonBRT also found that the length of bus rides was more consistent each day.

These results are similar to the impact of bus lanes in Boston and Everett, which also reduced travel times and have since become permanent. Arlington also decided to make its bus lane permanent this spring.

"These very low-cost, quick-build projects yielded very high impact benefits both in terms of bus performance but also bus experience," said Julia Wallerce, the Boston program director for the nonprofit Institute for Transportation and Development Policy, which manages BostonBRT.

The encouraging data comes as the MBTA tries to find ways to move its buses faster amid the nation's worst rush hour traffic. And it's gotten worse: The time it takes buses to complete their routes during rush hour has increased 17% between 2006 and 2018, according to the MBTA.

"It's taking longer for the buses to run through the system, particularly during peak [times] when our commuters are using it," MBTA operations chief Kat Benesh said at Monday's Fiscal and Management Control Board meeting.

The T has plans to improve the bus system. That includes working with cities and towns to implement more bus lanes, change bus routes and tweak traffic signals to give buses priority at intersections.

"Bus priority — we cannot emphasize enough — is what's really going to reduce the travel times and make these trips more reliable," Benesh said.

The transit agency says it has nearly $9 million set aside for bus improvements. And according to transit officials, riders can expect to see more bus lanes in Boston, Cambridge, Arlington, Somerville and Chelsea in the next couple of years.