After hundreds of hours of work from a diverse collaboration of academics, the Boston Police Department, the Boston Public Health Commission, and several Boston Cyclists Union interns, the city has far greater insight into the causes of bike crashes than ever before, thanks to an extensive new Cyclist Safety Report released by the city yesterday.

Mayor Thomas Menino also took the occasion to add a promising new goal for the city: to reduce the bike crash injury rate by 50% by 2020. The study seems poised to change the conversation around bike safety-and may even accelerate Boston’s bike boom.

The study’s well-timed release was tainted however by a math error in its “Findings” section. Both the Boston Globe and Boston Magazine are running corrections today on the number of bike crashes that involved a cyclist running a red light or a stop sign. It was originally reported as 28%, but the real figure is likely to be between 5.9% and 12%, (taking it either from the full number of crashes looked at (1,790), or only those which indicated a cause of some kind (891)).

This flaw and a few other calculation errors have been corrected in the report and appear to have been limited to the “Findings” section, which had a different author than the Boston Police Department (BPD) and Boston Emergency Medical Services (EMS) sections that follow. The actual numbers on running reds can be found on Page 43 of the report, in the BPD section.

The correct data indicates that while running red lights and stop signs is clearly causing crashes and should be discouraged, it is not the most dangerous behavioral factor measured. Riding against traffic was just as common, drivers “not seeing” the cyclist was 50% more common, and dooring was nearly twice as common, suggesting some additional enforcement priorities for the city. And any enforcement that targets cyclists should also be done in a way that helps ensure it does not discourage cycling–keeping in mind the city’s goal of increasing the Bike to Work rate to 10% by 2020.

Some familiar crash types, such as the right hook and left cross, are missing from the study because they have yet to be coded in this data-though that appears to be a future goal. The police Department’s study recommends training officers to use a sophisticated standard called the Pedestrian and Bicycle Crash Analysis Tool (PBCAT) to better classify crashes in the future.

Some of the more interesting findings and possible recommendations were:

• The number of crashes isn’t rising, but ridership is-which could indicate a “Safety in Numbers” effect. If it’s true, it means increasing ridership may play a part in making individuals safer.
• Taxis are twice as likely to be involved in doorings as cars-which makes the hackney industry a great target for driver education and design or technological solutions (pay attention MIT). The city has been working on a sticker for taxi doors for over a year now and may be close to implementation.
• People of college age are disproportionally affected by bicycle crashes-which indicates the city’s universities have a stake in creating safer street designs around their campuses, and an opportunity to educate their students on bike safety.
• Bike injuries and deaths may have cost between $6.2 and $46.7 million in 2010 alone.
• Bicycle crashes occur in every neighborhood, city council district and legislative district.
• Pedestrians hit by cyclists account for only 2% of all bike crash incidents in the Boston Police Data, and only 1.5% in the Boston EMS Data.

And one of the most powerful developments coming from the BPD study is yet to come. One of the biggest tasks in the study was taking out all the personal information in the police reports so they can safely be made available to various city departments, the advocates, researchers and perhaps even the public. The idea is to make them available in a new interactive crash map where neighborhood residents and transportation consultants alike would be able to get a good sense of what the existing problems might be on a street that is being reconstructed or repainted.

The study does not provide any new significant insights on helmet use and its effect on preventing crashes or injury, though it does mention that other studies have shown that when you are in a crash, helmets may reduce the risk of head injury by up to 85 percent and the risk of brain injury by up to 88 percent.

This is true. Wearing a helmet is the smart thing to do. But even if everyone did, it would not be likely to move the needle significantly on the total number of injuries from bike crashes in the city of Boston.
In 2010, according to a recent Boston Emergency Room study the Boston Public Health Commission was involved in creating in 2011, head injuries were only 2.2% (31) of emergency room visits for bicycle related incidents. Much more common were fractures and dislocations (398), open wounds (231) and sprains and strains (144).

The upshot is that there really is no magic bullet for bike safety. Reducing the bike crash injury rate by 50% is more likely to be accomplished by a comprehensive approach–with physically-separated bike facilities like cycletracks a necessary ingredient, but also biker and driver safety education, new legislation that encourages motorists to be more careful around cyclists and pedestrians, and many other elements.

One new tool to hit Boston this spring is truck sideguards on the city’s Public Works Department truck fleet. The largest pilot program of its kind, the program is meant to encourage private companies with trucks to follow suit. Buses and trucks were involved in the majority of cyclist deaths last year, and the addition of wheel guards for buses and sideguards for trucks would help make those types of crashes less serious.

The city is already beginning to address some of these approaches, including cycletracks proposed for Seaver St. in Roxbury and Mt. Vernon St. in Dorchester this year, but this new crash report can help us be smarter about the details. It also helps build the argument for building cycletracks in corridors where bike crashes are more frequent-such as the proposals for cycletracks around the Public Garden and down Malcolm X Blvd.

But more importantly–this crash study was a collaborative effort. If our community continues to foster these rich collaborations between Boston’s bright academic stars, advocacy groups, and government, the future will be bright for all modes of travel.

Heartfelt thanks go out to Rappaport Fellow Dahianna Lopez, BPD Commissioner Ed Davis, BPD Superintendent Daniel Linskey, BPD Captain Jack Danilecki, BPD’s Marjorie Bernadeau, Maria Cheevers, Treymayne Youmans and Carlos Cannon; Boston EMS chief James Hooley, EMS data analyst James Salvia, BPHC Commissioner Barbara Ferrer, Boston Area Research Initiative’s Dan O’Brien, Harvard School of Public Health’s David Hemenway, WalkBoston’s Dorothea Hass, and Boston Cyclists Union volunteers Ira Hubert, Jannik Mikkelsen, Erik Adams, Natasha Gayl, John Ferrante, and Rafael Medina who directly helped complete this research.