The Boston Cyclists Union's Interactive Crash Map

Welcome to the best source of online information available on bike crashes in the city of Boston! This map is created using ambulance run data from Boston Emergency Medical Services (EMS) from May, 2010 to July, 2011. Special thanks to the Menino Administration, Chief James Hooley and analyst James Salvia at EMS for their assistance and support.

Please use this map to help determine priorities for improvements in your own neighborhoods, and contact us when you do. We can help you advocate for them and we might already have contacts with neighbors of yours who are also working on the same issues!

PLEASE READ: This map is not completely accurate! Below the map there are a few very important caveats to be aware of on the map and the data.

Please read these important caveats on the data contained in the map above:

    • Due to the nature of the collection of this data, this map cannot be completely accurate. Data for each point and even the location of incidents all have the potential to be inaccurate. Use it as an indicator of larger patterns, but not as an accurate account of each individual crash.
    • The “incident” is determined by reports that are written by EMTs and the “impact type” field in the raw EMS crash data. When these two disagree, the written report is taken as the more reliable source. When both fields do not give enough information on the type of crash, it is categorized as “Unknown,” or if a motor vehicle was clearly involved, “Unknown MV.”
    • All vehicle speeds are generally reported by the victim or other witnesses to the crash, and recorded by the EMT on scene, and are thus simply educated guesses from people that may actually be experiencing shock or other factors that may affect their ability to estimate speed or recall events.
    • Locations are not always precise. They location given in the report is recorded by the EMT, but not all locations in the city present the EMT with an easy way to pinpoint them. For instance, two entries on the map are recorded as “Storrow Drive WB,” which is a street with no addresses facing it and very few cross streets.
    • Our sample size is still too small to make completely accurate predictions about patterns at particular intersections. The three incidents recorded at Cedar Street and the SW Corridor, for instance, might not indicate that every two months, there is an accident there. Only when we have years of data will we begin to be able to accurately measure accident rates in this way.
    • This data alone is not appropriate for making routing decisions. The presence or absence of incidents in a location should not be used to determine the relative safety of biking there as this data does not included ridership or traffic information; i.e. a location may be contain less incidents because bikers know to avoid it.

The map will be updated on a monthly basis for the foreseeable future. Each month will be added by the first day of the month after the following month. November’s data, for instance, will be added by January 1st. Updates will be announced via our Facebook page. Updates will be announced via our Facebook page.

Please feel free to let us know about any inaccuracies or incorrect locations you might find. We’d like to improve the accuracy of the data as much as possible.

Map and text Copyright Boston Cyclists Union. Please contact us for permissions.