Intersection where fatal bike crash happened is well-known danger zone

Police and crime investigators were on the scene after a bicyclist was fatally injured Friday. (David L. Ryan/Globe Staff

The busy Back Bay intersection where a bicyclist was fatally injured in a crash Friday morning was found to be the most dangerous crossroad in the city in a recent study.

There were 14 collisions involving cyclists at or near the intersection of Massachusetts Avenue and Beacon Street between 2009 and 2012 — more than at any other single location in the city during that span, according to data from police reports the Boston Area Research Initiative collected and mapped, with help from the Harvard Injury Control and Research Center and the Boston Cyclists Union.

The data used in the study is the most recent publicly available, according to pro-bike activists, who say there’s a dire need for more data to be collected so biking safety can be improved.

The intersection can be chaotic: The avenue runs through with two lanes in each direction, while Beacon, a one-way road, carries two additional lanes, and each roadway also has a right-turn lane at the intersection. There are bike lanes, crosswalks, a bus stop, a Hubway station, and curbside parking.

Pete Stidman, executive director of the Boston Cyclists Union, said the intersection and its numerous hazards are well-known to bike riders.

“It’s one of the main ways to get between Boston and Cambridge,” said Stidman. “Everybody [who bikes] in the city rides through that intersection all the time.”

He said another potential risk for both cyclists and drivers at that junction is that “you can catch a lot of speed coming off the Mass. Ave. Bridge,” which slopes down as it approaches the intersection.

Stidman said trucks and other large vehicles pose unique dangers for cyclists, particularly when they are turning.

He said a large percentage of cyclist fatalities in Boston involve collisions with large vehicles.

Not only does the sheer size and mass of a large vehicle increase the odds that a collision with one will leave a cyclist with significant, deadly injuries, but also drivers of large vehicles often cannot see as well around them as drivers of smaller cars and trucks.

Large vehicles also sometimes need to make wider turns at intersections that can be deceiving.

“A tractor-trailer may appear to be going left, but they are actually making a right turn,” said Stidman. “It’s really difficult for you to judge what they’re doing. ... Even if they know to look over their shoulder when they take a right turn, they really can’t see you.”

“A key thing I tell all cyclists is: be extremely aware when passing a large vehicle on the right,” he added.

The City of Boston has taken steps to try to prevent serious injuries and death in cases in which a pedestrian or cyclist collides with a large vehicle. In the fall, the city passed an ordinance that it said made Boston the first place in the country to require all large vehicles contracted by the city to install side-guards, or barriers, designed to prevent people from sliding underneath the vehicles.

The ordinance also required large, city-contracted vehicles to install mirrors to improve drivers’ visibility and to affix blind-spot awareness decals to their vehicles.

Stidman applauded the measures, and said he hoped to see similar requirements made at the state and federal levels.

And he said that other measures, including redesigning roadways, are needed to improve safety for cyclists.

Painted bike lanes, like the ones that run through the Mass. Ave-Beacon intersection can help, but the markings fade with time, Stidman said. And because they are typically installed between traffic and parking lanes, cyclists sometimes crash into, or are forced to maneuver around, double-parked vehicles and open doors.

“Paint is not a real barrier,” Stidman said. “it doesn’t prevent anyone from driving over them.”

He and other cyclists advocate for protected bike lanes, or cycle tracks, which separate riders from traffic. The city this year announced it plans to install protected bike lanes and protected intersections on a stretch of Commonwealth Avenue.

Stidman said he’d like to see protected lanes on Massachusetts Avenue. Data shows the thoroughfare is littered with other collision-prone spots besides its intersection with Beacon, including the second-worst location a few blocks away at the intersection with the westbound lanes of Commonwealth Avenue where there were 12 collisions in the 2009-2012 data.

The Boston Area Research Initiative’s data, used for a major report on cycling safety the city published in 2013, showed that while the number of cyclist-involved accidents in Boston increased slightly between 2009 and 2012, the popularity of biking increased by a much greater percentage during that span.

“So the risk to the individual rider has actually gone down,” Stidman said.

A similar trend of rising accidents coupled with increasing bike use has been observed statewide.

Stidman said that along with tangible safety measures, like improved signage and roadway markings, drivers, too, have generally become more cautious of cyclists as their numbers have grown.

“People have become much more aware that cyclists are out there because they see them everywhere,” said Stidman.

Efforts have also been made, including through police enforcement, to ensure both drivers and bicyclists obey traffic rules.

Data for more recent years, beyond 2012, is not publicly available, according to Stidman and others who have researched bike accidents in Boston. He also cautioned that the data that is available may not account for minor accidents or other collisions that may go unreported to police or other officials.

Advocates have for years pushed for better data collection.

“Understanding the cause of the crashes that are going on is important so we can begin to calculate what different interventions would do to the total number of crashes,” said Stidman.

An official at Boston’s Emergency Medical Services agency said Friday that a follow-up report to the city’s 2013 cycling safety study is in the works, but not yet ready for distribution. Meanwhile, Mayor Martin J. Walsh in March announced various measures to improve transportation, including using data to prevent vehicle, pedestrian, and bicycle collisions.