Boston will test a bus-only lane in Roslindale on Tuesday

Bus passengers in Roslindale might get a quicker ride Tuesday morning, as the city tiptoes into testing a bus-only lane on Washington Street.Josh Reynolds for The Boston Globe

Bus passengers in Roslindale might get a quicker ride Tuesday morning, as the city tiptoes into testing a bus-only lane on Washington Street.

The city will close off the inbound parking lane between Roslindale Square and the Forest Hills T station during the Tuesday rush, allowing buses clear passage past traffic. The test will be repeated again the following Tuesday.

The city chose Tuesdays because parking is already banned until 7 a.m. for street cleaning. The bus lane will extend the parking restriction until 9 a.m., allowing buses clear passage during the morning commute, when nearly 60 percent of all travelers on Washington Street are in a bus.

Boston has been flirting with the idea of a designated bus lane for months, and advocates had accused the city of dragging its feet. But officials had promised to test it before the end of the year. They expect to operate the lane on a daily basis next spring after a public hearing process.

On Tuesday morning, city workers will be out as early as 4 a.m. to deploy traffic cones and “cordon off the lanes” to make room for buses, said Gina Fiandaca, Boston’s transportation commissioner.

The lane test will happen amid ongoing road work that has caused congestion on Washington Street, and is expected to mostly wrap up by the end of December. During the two Tuesday tests, the road work will make it difficult to gauge how the bus lane impacts traffic flow.

Still, by testing the lane, officials will learn how to best position cones and communicate the parking changes, Fiandaca said. The city is already using electronic street signs to alert passengers to the plan.

“This is as much to test our operational bandwidth to keep that lane clear as it is to test the commute times because we know the roadway is not in its final configuration whereas in the spring it will be,” she said.

@StreetsBoston well, the rumors are true, the first test pilot for # betterbuses by @BostonBTD are true. Starting Tuesday 12am-9am inbound only apparently. pic.twitter.com/ViKrLHvFaO

— Mark Tedrow (@MarkinRozzie) December 8, 2017

The Washington Street test will come a week after a Boston philanthropy, the Barr Foundation, issued grants to municipalities that plan to test bus lanes, including in Arlington, Watertown, and Cambridge. It also comes about a year after Everett first shuttered an inbound lane of traffic on a stretch of Broadway during the morning commute.

Boston already has a bus-only lane along the Silver Line route in the South End and Roxbury. The new North Washington Street Bridge, which will be built over the next five years, will also have a bus lane.