MassDOT interactive crash cluster map
We maintain an interactive map showing the Top Crash Locations. The interactive map contains a number of different map layers which can be viewed by clicking LAYERS to see the various options, including the top 200 Intersection Clusters and HSIP clusters.
Crash geocoding
We produce high crash locations layers which are displayed on an interactive map using Geographic Information System (GIS) procedures.
You can find these geolocated crashes in the crash portal. The rate of successful geocoding is approximately 95%, but is not uniform for all police departments or crash locations.
Crash cluster methodology
The Registry of Motor Vehicles maintains crash data records which are used to help understand roadway safety issues. The MassDOT Traffic and Safety Section utilizes all located police crash reports to develop crash clusters to highlight areas with the largest safety concerns. The crash cluster analysis method, developed by MassDOT, is a comprehensive method designed to locate crash clusters based on a weighting of crash severity. At the heart of the method is a fixed search distance around each crash. This radius controls how far the application will search for adjacent crashes. Using a set radius, the analysis method finds nearby crashes and merges their areas together, thus creating clusters. If two distinct clusters are found to share a common crash, the two clusters are merged into a single cluster. This method of search-and-merge results in a set of many distinct clusters of different sizes and shapes. The application then stores these clusters to the GIS output file, along with the count of crashes within the cluster.
The clusters are then ranked by the number of Equivalent Property Damage Only (EPDO) crashes contained within their boundaries. The crash weighting was aligned with the calculated crash costs based on methodology in a 2017 FHWA report, “Crash Costs for Highway Safety Analyses”. So as not to end up just chasing fatal crashes, all of the fatal and injury crashes were weighted together. This resulted in any type of injury crash (including fatal, incapacitating or suspected serious, non-incapacitating or suspected non-serious and possible injury) having a weighting of 21 compared to a property damage only crash based on the calculations.
Top intersection clusters
The only crashes included for the intersection clusters are the ones in which the police officer specified that the crashes have one of the following junction types: Four-way intersection, T-intersection, Y-intersection, five point or more. The intersection cluster analysis uses the three most recent years of closed crash records. The fixed distance search for clustering crashes is 25 meters (82 feet). For the Top 200 ranking, the highest 200 ranked intersection clusters across the Commonwealth were included. For the Top 5% MPO intersection clusters, the intersection clusters within each Metropolitan Planning Organization (MPO) were counted and ranked and the top 5% were included. The top 5% of crash clusters within each town were also identified. The crash clusters were named based on the highest functional classification roadway within the cluster, followed by the roadway with the second highest functional classification. In instances where there were two roadways with the identical classification, the first street name selected was the street with the longest segment contained within the cluster. Note that the area encompassing the crash cluster may cover a larger area than just the specific cluster named so it is critical to view these spatially.
Top pedestrian & bicycle clusters
The crash cluster analysis methodology for both the top pedestrian and the top bicycle crashes uses a fixed meter search distance of 100 meters (328 ft.). Crashes involving collisions between motor vehicles and pedestrians (or separately bicyclist for the bicyclist clusters) were identified by using the non-motorist type (now called the vulnerable user type) and, also where the first harmful event or most harmful event being a collision with a pedestrian or cyclist within the database. Because of the relatively small number of reported pedestrian and bicyclist crashes in the crash data file, the clustering analysis uses crashes from the most recent ten year closed crash period. For the Top 5% MPO intersection clusters, the pedestrian and bicyclist clusters within each MPO were counted and ranked and the top 5% were included. The top 5% of crash clusters within each town were also identified. Additionally, due to the larger geographic area encompassed by both the pedestrian and the bicycle crash clusters, it was difficult to name them so they were left unnamed but can be viewed spatially.
Highway Safety Improvement Program (HSIP) eligibility
An HSIP-eligible location is a crash cluster that ranks within the Top 5% of each MPO. The interactive map contains the various HSIP map layers. All of our HSIP Clusters and closed crash year GIS data files can be searched and downloaded from the MassDOT Open Data Portal. Refer to the HSIP page for more details.
Notice
MassDOT makes no representation as to the accuracy, adequacy, reliability, availability or completeness of the crash records or the data collected from them and is not responsible for any errors or omissions in such records or data. Under no circumstance will MassDOT have any liability for any loss or damage incurred by any party as a result of the use of the crash records or the data collected from them. It should be noted that the Top Crash Locations Report was compiled under the authority of United States Code Title 23, Section 148, Highway Safety Improvement Program, sponsored by the Federal Highway Administration. The compilation of such information is, therefore, subject to the limitations of Section 148 (g) (4) which states: DISCOVERY AND ADMISSION INTO EVIDENCE OF CERTAIN REPORTS, SURVEYS, AND INFORMATION - Notwithstanding any other provision of law, reports, surveys, schedules, lists, or data compiled or collected for any purpose relating to this section, shall not be subject to discovery or admitted into evidence in a Federal or State court proceeding or considered for other purposes in any action for damages arising from any occurrence at a location identified or addressed in such reports, surveys, schedules, lists or other data.