This document is draft and has not gone through the internal editorial review process.

Appendix B: Existing Conditions Data Analysis

2 Overall Fatality Trends

This section uses data from FARS to analyze overall fatality trends in for the region. This is done by looking at long-term fatality trends and by comparing the region’s fatality rates to peer areas.

Analyzing long-term fatality trends helps tell the story of the region’s progress on safety over time, which can inform future progress. Previous advances in transportation safety technology, such as the rising usage of seat belts, airbags, and more considerate vehicle design, helped drive fatality numbers down in the region.3 New technological advances complemented by effective investments in other areas, such as vehicle design, self-enforcing roadway design, education, and “right-sized” enforcement, will assist the region in its pursuit to reach Vision Zero.

Later in this section, the Boston region is compared to similar regions in other states. This comparison is shown to benchmark the region and to encourage future communication of best practices and lessons learned between the MPO and its peer organizations. Given the Federal Highway Administration’s (FHWA) commitment to zero deaths, the vision of no roadway fatalities is shared by the entire country and applicable to each MPO.4

The rest of this section goes into more detail, key takeaways for this section include the following:

Long-Term Trends

The historical fatality data from FARS are shown in Figure 2.1. The data in this figure are smoothed with a five-year rolling average to account for the inherent randomness in fatal crashes and to make long-term trends easier to observe. Data points every five years are labeled.

Between 1980 and 2022, the five-year average of Boston region fatalities experienced a general downward trend, decreasing by 68 percent over the entire time period. From 1980-2000, fatalities decreased at a rate of approximately 10 fatalities fewer per year on average. Since 2000, the rate of decline in fatalities slowed dramatically to approximately one fatality fewer per year on average. The trend of fatality rates declining over time is fairly consistent, with exceptions in the periods between 1987-1989, 2000-2004, and most recently in 2020-2022.

Figure 2.1 | Long-Term Fatality Trend (1980–2022)

Source:  Fatality Analysis Reporting System (FARS), National Highway Traffic Safety Administration (NHTSA).

Note:      Data from FARS and MassDOT IMPACT tool may not match exactly due to data processing discrepancies. Data from FARS also include fatalities on Interstates and access-controlled roads.

This trend for the region compares favorably to the national trend, seen in Figure 2.1. Nationally, according to FARS, fatalities decreased approximately 17 percent from 1980 to 2022, a much smaller decrease than the 68 percent seen in the region. Additionally, the national fatality numbers have constantly increased in the past decade, increasing by 20 percent from 2014 to 2022. In the same time period, the numbers have marginally decreased in the region.

If the fatality numbers in the region continue to decrease at a rate similar to 1980-2000, the region would reach Vision Zero in the next 10-15 years. If fatalities continue to decrease at a rate similar to the past two decades, the region will not reach Vision Zero for another 100 years. Effective and strategic investments must be made in transportation safety to reverse the plateaued trend of recent years and enable the region to reach Vision Zero.

Comparison to Peer Areas

Despite the challenges outlined above, the region maintains some of the lowest fatality rates among peer metropolitan areas. The following metropolitan areas were analyzed using fatality data from FARS and population data from the US Census Bureau to develop fatality rates per population.

• Philadelphia, PA
• Baltimore, MD
• Washington, DC
• Providence, RI
• New York City, NY

Peer MPOs were chosen based on proximity (all MPOs are in the mid-Atlantic or New England regions), similar sizes, and land use patterns.

Figure 2.2 shows the fatality rate, measured in fatalities per 100,000 residents, from 2018 to 2022. Among these peers, the Baltimore and Philadelphia regions average between 7 and 8 fatalities per 100,000 residents, the Washington and Providence regions average between 5 and 6, and New York City and Boston average between 3 and 4. The Boston region has the lowest fatality rate out of all these peers, and its 2023 fatality rate is approximately 3.5 fatalities per 100,000 people.

Boston is most similar to New York, both in terms of rate of fatalities and recent trends. Both regions saw decreases from 2018 to 2021 before increasing slightly in 2022. Because of these similarities, Boston may want to study some of the Vision Zero actions taken by the New York City region. Boston may also consider some of the more recent safety strategies from Providence, as the Providence region was the only region to experience a recent downward trend in fatality rate, decreasing from approximately 6 fatalities per 100,000 residents in 2021 to just under 5.5 in 2022.

Regardless of their peers, the region’s low fatality rates show that current safety strategies are making an impact. In addition to studying other regions, the region should expand upon its proven programs for crash reduction and continue its existing Vision Zero work to eventually meet the Vision Zero goal.

Figure 2.2 | Fatality Rate for Peer MPOs Compared to the Boston Region (2018–2022)

Source: Fatality data from FARS, NHTSA. Population data from the American Community Survey, US Census Bureau.

Note:      Data from FARS include fatalities on Interstates and access-controlled roads.

3 Current Trends

While long-term historical trends are important for setting the stage and telling the overall story of safety in the region, the specific contributing factors for those crashes can change over time. This section reviews and breaks down more recent crash data to identify current contributing factors linked to the most common and highest density crash types.5 Crashes are analyzed by severity, by time of day and year, by roadway type and ownership, and by other factors to help predict factors that may lead to more crashes in the future.

These breakdowns, combined with the emphasis area analysis in Section 4, will help the region focus on the most vital and over-represented crashes and will enable the region to prioritize solutions, strategies, and actions to maintain progress on the road to Vision Zero.

Key takeaways for this section include:

Crash Severity

From 2018 to 2022, a total of 188,683 roadway crashes occurred in the region, with 2 percent (3,986 crashes) resulting in fatalities or serious injuries. Overall, less severe crashes (KABCO injury severity levels C and O) accounted for more than 85 percent of total crashes.

To quantify the economic impact of crashes, cumulative crash costs were calculated for each severity level using the 2024 recommended comprehensive crash unit costs developed by MassDOT for highway safety analysis.6 These cumulative costs include both direct economic costs (e.g., medical expenses, emergency services, congestion costs) and quality-adjusted life years values, which estimate the societal and individual impacts of reduced health and lifespan due to crashes.

Table 3.1 summarizes the total number of crashes by severity level, along with the crash unit cost and corresponding cumulative crash costs for the region between 2018 and 2022. Over this period, crashes incurred an estimated total cost of $26.5 billion, averaging around $5.3 billion per year. Fatal and serious crashes make up over 46 percent of these crash costs alone. Evenly distributing the cost of crashes among residents of the region would result in crashes costing each resident over $1,500 each year.

Table 3.1 | Crashes by Injury Severity Level (2018–2022)

Source:  Crashes from the MassDOT IMPACT Portal; Crash costs from Crash Costs for Highway Safety Analysis, MassDOT.

Crashes by Time

Travel behaviors and crash frequency are correlated with time of day and day of the week. The total amount of vehicle miles traveled (VMT), and therefore, the opportunities for crashes, is generally greater on weekdays when people are driving to and from jobs compared to the weekend. Additionally, while more people drive during daytime hours, the lack of adequate lighting conditions and lower amounts of traffic can lead to higher speeds and severe crashes at night.7

To better understand the temporal crash patterns, the day was further divided into six four-hour periods. Figure 3.1 and Figure 3.2 show the distribution of total crashes as well as fatal and serious injury crashes across these time periods by day of week. Weekday afternoon periods (2 PM to 6 PM) experienced the highest fatal and serious injury crash frequency, closely followed by weekday morning periods (6 AM to 10 AM). Given that both periods include peak commuting times, the high crash frequency is likely attributable to higher traffic volumes and increased traffic congestion.

While 28 percent of all roadway crashes occurred during evening, late night, or overnight hours (6 PM to 6 AM), 40 percent of the fatal and serious injury crashes occurred during the same time period. This suggests that while more crashes happen in the daytime, nighttime crashes are more likely to result in severe outcomes. Despite the overwhelming majority of these fatal and serious injury crashes happening when the sun is down, only 7 percent of crashes in this time period occurred in dark unlighted areas compared to 70 percent occurring during dark lighted areas. This indicates that, while lighting is an important contributing factor in nighttime crashes, it’s not the only contributing factor. Outside of lighting, the prevalence of drivers under the influence is correlated with nighttime crashes. During these hours, drivers under the influence are eight times more likely (13 percent) to be a cause of a fatal or serious injury crash compared to daytime hours (2 percent), per MassDOT IMPACT data.

Figure 3.1 | Total Crashes by Time of Day and Day of Week (2018–2022)

Source:  MassDOT IMPACT Portal.

Figure 3.2 | Fatal and Serious Injury Crash by Time of Day and Day of Week (2018–2022)

Source:  MassDOT IMPACT Portal.

Crashes by Functional Classification

One method to classify roadway types is by functional classification, which is a hierarchy of road types that serve different needs. Arterials are generally main thoroughfares that limit cross-traffic and are often controlled by traffic signals, while collectors generally serve to funnel traffic from local roads on to the arterials. Local roads serve individual houses and neighborhoods and make up the largest percentage of roadways by mileage, but often see the lowest traffic volumes and lowest average speeds. Analyzing crashes by roadway type influences further systemic analysis of crashes and can help the MPO put together packages of systemic roadway projects.

Between 2018 and 2022 in the region, principal arterials accounted for the largest share of both total crashes (42 percent) and fatal and serious injury crashes (38 percent). However, minor arterials showed a disproportionately higher percentage of fatal and serious injury crashes (33 percent) compared to their share of total crashes (28 percent).Table 3.2 presents a detailed breakdown of fatal and serious injury crashes, total crashes, and fatal and serious injury crashes with VRUs involved by functional classification.8

Regarding fatal and serious injury crashes that involved at least one VRU, while principal arterials still accounted for the plurality (39 percent), these crashes were more likely to occur on local roads (16 percent vs. 14 percent) and less likely on minor arterials (30 percent vs. 33 percent) compared to fatal and serious injury crashes where no VRUs were involved.

Table 3.2 also normalizes these crash breakdowns by the centerline mileage of roadways in each functional classification. All types of crashes, regardless of severity of VRU-involvement, occur at a greater rate per mile on principal arterials and minor arterials. Two times the amount of crashes per mile are likely to occur on minor arterials compared to major collectors, and two times the amount of crashes per mile are likely to occur on principal arterials compared to minor arterials. This is likely due to the higher vehicle volumes and therefore more opportunities for crashes on roadways of higher functional classifications.

Table 3.2 | Crashes by Functional Classification (2018–2022)

Source:  MassDOT IMPACT Portal.

Note:      The By Mileage column equates to the number of crashes divided by the centerline mileage of roadways in that functional classification.

Note:      As noted in the Data Sources & Processing section, fully access-controlled roadways, which includes Interstates and Principal Arterials—Other Freeways & Express, were removed from this analysis and are not shown in this table.

4 Emphasis Areas

In conjunction with the analyses completed in Section 3, summarizing crashes by emphasis areas will further narrow the focus on specific crash types and assist in the prioritization of investments in the region. The Massachusetts Highway Safety Improvement Program (HSIP) identifies emphasis areas for the entire Commonwealth.11 Paired with the conclusions from Section 3, these emphasis areas are a helpful framework for identifying common crash issues, analyzing contributing factors, and linking them with a set of countermeasures and strategies.

Key takeaways for this section include:

Emphasis areas studied in this plan include the following:

• Intersections: Crashes that occur within intersections or are related to the operation of intersection approaches.
• Lane Departure: Crashes that occur when a vehicle intentionally or unintentionally crosses an edge or centerline or otherwise leaves the traveled way.
• Older Drivers: Crashes where one or more of the drivers involved is at least 65 years old.
• Pedestrians: Crashes that involve a pedestrian. Pedestrians include people on foot or using a mobility device such as a wheelchair.
• Younger Drivers: Crashes where one or more of the drivers involved is between 15 and 20 years old.
• Motorcyclists: Crashes that involve a motorcyclist.
• Distracted Driving: Crashes where the driver was distracted by an electronic device, a passenger, or an external distraction outside the vehicle.
• Bicyclists: Crashes that involve a bicyclist.
• Impaired Driving: Crashes where the driver was suspected to be under the influence of alcohol.
• Large Vehicles: Crashes that involve large trucks, tractor trailers, buses, or other large vehicles.
• Speeding: Crashes where the driver exceeded the authorized speed limit.
• Occupant Protection: Crashes where either the driver or a passenger is not wearing a seat belt.

More specific information, including the exact queries used to filter to these emphasis areas, are available on MassDOT’s website .

Table 4.1 lists the fatal and serious injury crashes for each emphasis area for both the Boston region and the Commonwealth of Massachusetts, the percentage of total fatal and serious injury crashes within each emphasis area, and the change in fatal and serious injury crashes from 2018 to 2022. Emphasis areas that are notably more prevalent in the region compared to the Commonwealth are highlighted in red.

To narrow the focus of this analysis, the following six emphasis areas emerged as key emphasis areas to address in the Boston Region Vision Zero Action Plan.

• Intersections
• Lane Departure
• Vulnerable Road Users (A combination of Pedestrians and Bicyclists)
• Older Drivers
• Large Vehicles
• Speeding

The Intersections, Lane Departure, and Older Drivers emphasis areas were the top three emphasis areas in terms of the percentage of the region’s fatal and serious injury crashes. Given Vision Zero’s focus on the safety of people outside of vehicles, the Pedestrian and Bicyclist emphasis areas were combined for a VRU emphasis area. When these categories are combined, the VRU emphasis area is the second most-prevalent emphasis area by crash percentage. Additionally, Intersections, both VRU categories, and Older Drivers were over-represented when compared to the rest of Massachusetts. All of these emphasis areas represent over 20 percent of fatal and serious injury crashes in the region each.

In addition to the above emphasis areas, the Large Vehicles emphasis area was also over-represented compared to the rest of the Commonwealth. While these crashes only contribute to 5 percent of fatal and serious injuries in the region, this emphasis was consistently noted by key regional stakeholders as an important focus moving forward.

The Speeding emphasis area, while not one of the emphasis areas with the largest number of fatal and serious injury crashes, was one of the fastest growing areas over the past five years. Speeding-related fatal and serious injury crashes increased by over 90 percent from 2018 to 2022, which is the second-fastest growing emphasis area except for bicyclists. Additionally, high vehicle speeds was mentioned repeatedly as a key issue by stakeholders. Because of the recent high growth of this emphasis area and the feedback of stakeholders, Speeding emerged as the final emphasis area.

Despite the fact that the other emphasis areas were not selected as part of the key emphasis area list, this does not mean they are not important for the region and individual municipalities to focus on when thinking about how to improve roadway safety. Strategies and actions in the plan will still relate and address these emphasis areas, as several are interconnected. The focus of the majority of the strategies and actions in the Vision Zero Action Plan, however, will be on the key emphasis areas.

Because of their outsized importance, deeper dives into the contributing factors of the six key emphasis areas are provided below to better tailor the strategies and actions of the region’s plan.

Intersections

Intersection crashes include those crashes that are directly located within intersections or related to the operation of intersection approaches. These are critical points of conflict among various road users, including motorized vehicles, pedestrians, and cyclists, leading to a high incidence of crashes.

Among all the identified emphasis areas, intersection-related crashes were the most common type of fatal and serious injury crashes from 2018 to 2022, contributing to 44 percent of the region’s total. While these crashes were slightly over-represented compared to the statewide percentage of 40 percent, they remained relatively stable at just under 400 per year over the five-year period, except for a brief decline in 2020, likely due to reduced traffic volumes during the pandemic. By 2022, these crashes had increased by 7 percent compared to 2018, a much slower rate than the statewide increase of 16 percent.

Figure 4.1 | Intersection-Related Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

Given the distinct safety challenges posed by each intersection's unique combination of geometry, configuration, and traffic control, intersection-related crashes were further analyzed by intersection type and traffic control type. As indicated in Table 4.2, four-way intersections and T-intersections accounted for the majority (94 percent) of fatal and serious injury intersection crashes. Additionally, the proportion of fatal and serious injury crashes relative to total intersection crashes increased with the number of intersection approaches, likely due to increased complexity of intersection configurations.

Table 4.2 | Fatal & Serious Injury Crashes by Intersection Type (2018–2022)

Source:  MassDOT IMPACT Portal.

Among fatal and serious injury crashes at T-intersections and four-way intersections, nearly half (45 percent) occurred at signalized intersections, followed by 32 percent at uncontrolled intersections. To enhance intersection safety, potential countermeasures include optimizing signal timing, prohibiting right turns on red, or converting conventional intersections to roundabouts. The selection of specific interventions should consider factors such as location, traffic volumes, and the walkability of the surrounding area.

Vulnerable Road Users

VRUs face unique challenges and a higher risk of injury compared to other road users. While walking and biking can offer significant health and environmental benefits, VRUs are more susceptible to serious injuries and fatalities when involved in collisions with motor vehicles. From 2018 to 2022, while VRU crashes accounted for only 5 percent of total roadway crashes, they made up 27 percent of fatal and serious injury crashes within the region. If a VRU is involved in a crash, they are eight times more likely to be killed or seriously injured compared to a person in a vehicle.

Table 4.3 | Fatal & Serious Injury Crashes by VRU Involvement (2018–2022)

Source:  MassDOT IMPACT Portal.

Note:      Numbers in the Total row may differ from other tables and figures due to inconsistent data availability for certain fields.

Figure 4.2 illustrates the annual number of fatal and serious injury crashes involving pedestrians and bicyclists over a five-year period. Between 2020 and 2022, these crashes steadily increased from 177 to 252, a 42.4% growth in just three years. This upward trend is consistent with the overall pattern observed across Massachusetts. However, the rate of increase in the region was more pronounced, particularly for crashes involving bicyclists, which saw a substantial 90.6% rise compared to the 60.9% increase experienced statewide. It is unclear whether this substantial rise is due to a decrease in VRU safety conditions or due to an increased use of active transportation and more exposure for VRUs.

Figure 4.2 | Vulnerable Road User Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

A deeper analysis of VRU fatal and serious injury crashes reveals contributing factors.

• Location: While the majority (52 percent) of VRU crashes occur at non-intersections (i.e., mainline) locations, a higher percentage of VRU crashes occur at intersections compared to non-VRU crashes. Among those mainline crashes, the common roadway type for severe VRU crashes were principal arterials, accounting for 40 percent.
• Speeds: 30 mph was the most common speed limit associated with severe VRU crashes (25 percent), but roadways with a 55 mph speed limit, particularly minor arterials, exhibited the highest proportion of fatal and serious VRU crashes relative to all VRU crashes on those roads (40 percent of VRU crashes on minor arterials with a speed limit of 55 mph resulted in fatalities or serious injuries).
• Lighting Conditions: Over half (57 percent) of VRU fatal and serious injury crashes occurred during daylight hours, followed by crashes under dark lighting conditions which accounted for 30 percent. VRUs face an increased risk in dark conditions without lighting, as 28 percent of the VRU crashes under such conditions resulted in a fatality or serious injury
• Vehicle Types: Although large vehicles were involved in only 5 percent of severe VRU crashes, their involvement nearly doubled the likelihood of a VRU crash resulting in a fatality or serious injury since these vehicles have a much higher impact force on the VRU compared to other vehicle types.
• Impairment: While data are not available for the Boston MPO region, the MassDOT VRU Safety Assessment indicates that, in the entire Commonwealth, 25 percent of pedestrians and 16 percent of bicyclists who are hospitalized from crashes were under the influence of alcohol or drugs at the time of the crash.

Lane Departure

A lane departure crash, as defined by FHWA, is a crash that occurs after a vehicle crosses an edge line or a center line or otherwise leaves the traveled way. Besides intersection crashes and VRU crashes, lane departures are the third leading cause of fatal and serious injury crashes both statewide and within the region.

Between 2018 and 2022, lane departure crashes accounted for 21 percent of fatal and serious injury crashes in the region, despite comprising only 4 percent of all crashes. This significant disparity highlights the high severity potential of lane departure crashes. Like the statewide upward trend, fatal and serious injury lane departure crashes in the region gradually increased from 138 in 2018 to 197 in 2022, a 43 percent rise over five years, comparable to the statewide increase of 38 percent. These trends indicate a persistent challenge in preventing vehicles from leaving their intended travel lanes.

Figure 4.3 | Lane Departure Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

The causes of lane departure crashes are multifaceted, ranging from environmental characteristics (such as lighting and weather conditions) and roadway attributes (such as curvature and grade) to driver behavior. Contributing factors include:

• Roadway Type: Two-way undivided roadways were the most common roadway type for these severe crashes, accounting for 67 percent of all fatal and serious injury lane departure crashes.
  Therefore, this emphasis area should consider placing greater focus on addressing cross-centerline crashes compared to cross-median issues.
• Collision Type: Collisions with fixed objects such as trees (22 percent) and utility poles (26 percent) are the most frequent “first harmful event” types.
• Lighting Conditions: Lane departure crashes occurring during dusk are more likely to result in fatalities and serious injuries (20 percent) compared to daylight (13 percent), highlighting the need for improved visibility measures during transitional lighting conditions.

Additionally, dangerous driver behaviors were found to greatly increase the risk of lane departure crashes. More than half (51 percent) of fatal and serious injury crashes involving impaired driving and nearly half (46 percent) of speeding-related fatal and serious injury crashes ended in a lane departure. As shown in Table 4.1, lane departures normally make up 21 percent of all fatal and serious injury crashes. Therefore, impaired driving or speeding doubles the chance of having a fatal or serious injury lane departure crash, emphasizing the importance of context-sensitive roadway design and awareness efforts targeting these high-risk behaviors.

Older Drivers

As drivers age, physical and cognitive changes that are part of the normal aging process can affect their ability to drive safely and make them more vulnerable to fatal and serious injuries. Many features of the current roadway systems, licensing practices, and vehicles were not originally designed to accommodate older drivers. Within the region, 21 percent of fatal and serious injury crashes involved older drivers (drivers aged 65 and older), slightly higher than the statewide share of 20 percent, which underscore the safety concerns for this particular demographic.

As demonstrated in the five-year trend in Figure 4.4, fatal and serious injury crashes involving older drivers first experienced a drastic increase of 22 percent in 2019 compared to the 2018, followed by a 31 percent decline in 2020 due to pandemic-related impacts, and then quickly rebounded to 2019 levels within the next two years. Overall, the rate of increase in older driver-related fatal and serious injury crashes over the five-year period slightly outpaced the statewide rate, indicating a growing need for targeted safety interventions.

Figure 4.4 | Older Driver Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

Several key factors can contribute to the increased risk of fatal and serious injury crashes involving older drivers. These include age-related declines in physical and cognitive function, underlying medical conditions, individual driving habits, and limitations in roadway design and vehicle features.12

• Lighting Condition: The majority (76 percent) of fatal and serious injury crashes involving older drivers occurred during daylight hours. However, dark, unlit conditions might be the most dangerous scenario for older drivers, as 6 percent of total older driver-related crashes in these conditions resulted in a fatality or serious injury (compared to 2.2 percent during daylight hours). This highlights the need for improved roadway lighting in areas with significant older driver populations.
• Medical Condition: Analysis of driver contributing circumstances indicates that the likelihood of fatal and serious injury crashes attributed to driver illness, or a history of heart conditions, epilepsy, or fainting was nearly twice as high in crashes involving older drivers compared to those without. Outside of driver contributing circumstances, the increased fragility of older drivers’ medical conditions makes them more likely to suffer a severe injury compared to younger drivers.
• Land Use: Fatal and serious injury crashes involving older drivers showed a greater concentration in commercial areas than in residential areas. High-density business/commercial centers posed the highest risk, with over 3 percent of all crashes in these areas ending in a fatality or serious injury (other areas were generally between 1 and 2 percent). This may be due to the increased complexity of busy environments, including higher pedestrian and vehicle traffic, and more frequent unexpected events like sudden stops.
• Intersection Type: Among all intersection types, five-point or more intersections had the highest proportion of fatal and serious injury crashes (5 percent) relative to all older driver-related crashes. This suggests that the increased complexity of these intersections may overwhelm some older drivers, which emphasizes the potential benefits of simplified designs and enhanced signage.

Speeding

Speeding has consistently been identified as a contributing factor to fatal and serious injury crashes by stakeholders in the region. While speed-involved crashes only accounted for a small proportion (5 percent) of the total fatal and serious injury crashes, the Boston region experienced a substantial 91 percent increase in these crashes from 2018 to 2022. Although a similar increase (85 percent) was observed statewide, addressing speeding-related issues remains a critical priority for the region.

The yearly variation in speeding-related fatal and serious injury crashes is shown in Figure 4.5. Mirroring the upward trend in lane departure crashes, speeding-related fatal and serious injury crashes also exhibited a consistent increase over the five-year period. Notably, 2022 recorded the highest year-over-year growth rate of 45 percent.

Figure 4.5 | Speeding-Related Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

As previously discussed in the lane departure emphasis area, speeding behavior can be a significant contributing factor to lane departures, given that nearly half of speeding-related fatal and serious injury crashes also involved a lane departure. Additionally, speeding was also found to be prevalent in severe crashes involving impaired driving and motorcyclists. In fatal and serious injury crashes, impaired drivers were three times more likely to be speeding compared to non-impaired drivers (14 percent vs. 5 percent), and motorcyclists were observed to have almost double the percentage of speeding compared to car drivers (9 percent vs. 5 percent). Further analysis of potential risk factors associated with speeding-related fatal and serious injury crashes suggests that:

• Posted Speed Limit: In fatal and serious injury crashes involving speeding, the most common speed limit was 30 mph (30 percent), followed by 25 mph and 35 mph, each at 10 percent of all speeding-related fatal and serious injury crashes. Since lower speed limits typically occur on local roads with lower design standards and higher non-motorist activity, speeding in these areas was more likely to result in a fatality or serious injury. This suggests the need for a careful review of speed limits on local roads and more self-enforcing roadway design to discourage speeding.
• Functional Classification: The most common roadway functional classes for fatal and serious injury crashes involving speeding were principal arterials (33 percent) and minor arterials (29 percent). While the proportion of fatal and serious injury crashes relative to total speed-related crashes did not vary significantly across different functional classifications, the higher prevalence of speeding on local roads and major collectors still deserves attention.
• Time of Day: Evening (6 PM to 10 PM) and Late night (10 PM to 2 AM) periods had the highest percentages of fatal and serious injury crashes involving speeding. Compared to daytime periods, the percentage of speeding during these hours was nearly three times higher, indicating a possible need for targeted driving engagement and speed monitoring. However, despite a lower speeding rate, the mid-day period (10 AM to 2 PM) had the highest likelihood of speeding-related crashes resulting in severe injuries (12 percent of total speeding-related crashes were fatal and serious injury crashes). This may be due to higher level of pedestrian and cyclist activity during this time, which increases the risk of severe collisions when speeding occurs.

Large Vehicles

Based on the MassDOT HSIP emphasis area definition, large vehicles include buses, single-unit trucks, and tractor-trailers. From 2018 to 2022, large vehicles were involved in 5.4 percent of fatal and serious injury crashes, slightly higher than the statewide percentage of 5.3 percent. Of the 215 large vehicle-related fatal and serious injury crashes recorded during this period, 17 percent involved buses, 41 percent involved single-unit trucks, and 31 percent involved at least one tractor-trailer.

As illustrated in Figure 4.6, the number of fatal and serious injury crashes involving large vehicles rose by 26 percent from 2018 to 2019, followed by a 35 percent decline in 2020, likely due to reduced overall traffic. From 2020 to 2022, the number of such crashes remained steady at 48 per year. Overall, the number of large vehicle-related fatal and serious injury crashes in the region has been increasing at a slower rate compared to the statewide trend.

Between 2018 and 2022, 263 people were killed or seriously injured in crashes involving large vehicles. 56 percent of them were vehicle drivers, 23 percent were passengers, and 21 percent were VRUs.

Figure 4.6 | Large-Vehicle-Related Fatal and Serious Injury Crashes (2018–2022)

Source:  MassDOT IMPACT Portal.

Potential contributing factors identified for large vehicle-related fatal and serious injury crashes include:

• Roadway Type: The majority of fatal and serious injury crashes involving large trucks occurred on principal arterials (42 percent) and minor arterials (30 percent). Over half (58 percent) of these fatal and serious injury crashes occurred on two-way undivided highways, indicating less separation of opposing lanes may contribute to increased crash risk.
• Speed Limit: While 30 mph was the most common speed limit for large vehicle-related fatal and serious injury crashes (24 percent), roadways with a speed limit of 55 mph were associated with a significantly higher risk of fatal or serious injuries.
• Time of Day: 79 percent of large vehicle-related fatal and serious injury crashes occurred during the daytime (6 AM to 6 PM). However, crashes involving large vehicles during nighttime were more at risk of fatalities or serious injuries compared to daytime, especially during the overnight period (2 AM to 6 AM), when the presence of other contributing factors like inadequate lighting, speeding, and driver fatigue is more likely. Analysis of lighting conditions also suggests that large vehicle-related crashes under dark, unlit conditions had the highest likelihood (4 percent) of resulting in fatalities and serious injuries.
• Occupant Protection: 92 of 603 vehicle occupants (17 percent) involved in large vehicle fatal and serious injury crashes were not wearing a seat belt at the time of the crash. Of the 92 unrestrained occupants, 66 (72 percent) were killed or seriously injured in the crash, indicating that lack of seat belt use significantly increases a person’s risk of severe injury or fatality, particularly in a large vehicle involved crash. The majority (58 percent) of unrestrained vehicle occupants that were killed or seriously injured in the crash were passengers.

5 Subregion Analysis

The Boston region is divided into eight subregions to promote coordination among local cities and towns and to better understand transportation needs in each subregion. While previous sections of this report focused on the entire region, it is important to recognize the potential of significant variations at more local levels. To gain a more detailed understanding of the unique safety challenges faced by each subregion and to inform the development of more effective and locally adapted safety strategies, this section examines the existing safety performance and identifies top emphasis areas for each of the eight subregions.

The eight subregions in the Boston Region MPO are listed below.

6 Municipality Analysis

The MPO region encompasses 97 cities and towns, stretching from Boston to Ipswich in the north, Marshfield in the south, and to approximately Interstate 495 in the west. Building upon the regional and subregional analyses of safety performance over the past five years, this section focuses on investigating the existing conditions at the municipal level. The top 10 municipalities with the highest number of fatal and serious injury crashes and the top 10 municipalities with the highest fatal and serious injury crash rates are summarized here. Similar to Section 5, each of the municipalities has an overview of crashes and the identification of top emphasis areas. By identifying municipalities with the most significant fatal and serious injury crash concerns, the region can prioritize safety investments in those areas of greatest need to maximize the potential safety impacts.

Key takeaways for this section include:

Municipality Summary

Table 6.1 and Table 6.2 show a summary of the 10 municipalities in the region with the most fatal and serious injury crashes and the highest fatal and serious injury crash rates, respectively.14 Both total crashes, regardless of severity, and fatal and serious injury crashes are summarized. For both the total crashes and the total fatal and serious injury crash categories, the following information is presented:

• The total number of crashes within each category.
• The percentage of all of the region’s crashes in each category within each municipality.
• The change in the total number of crashes in each category from 2018 to 2022.
• The total number of crashes in each category per 100,000 residents.

In general, out of the top 10 municipalities shown in Table 6.1, the municipalities with the highest numbers of fatal and serious injury crashes (Boston, Lynn, Quincy, and Cambridge) are decreasing while the those with lower numbers are increasing (Newton, Revere, Malden, Chelsea, Framingham, and Weymouth). Chelsea has experienced a surge in fatal and serious injury crashes in recent years, almost doubling from 12 in 2018 to 23 in 2022. Weymouth (90 percent) and Framingham (73 percent) have also experienced significant increases in recent years.

The top 10 municipalities shown in Table 6.2 are generally municipalities that are on the outer edges of the region and are more suburban in land use compared to the core of the region. The exceptions to this are Lynn, Saugus, and Chelsea, all denser municipalities north of Boston. For the other seven towns, this suggests a link between some of the land uses and policies of the outer suburban region as it relates to higher crash rates. For Lynn, Saugus, and Chelsea, more study is needed to identify potential causes for the higher-than-expected crash rates.

7 Next Steps

This existing conditions analysis provides the foundation for future data analysis, policy evaluation, and strategy selection. Findings offer a snapshot of roadway safety in the region, which may be used in public and stakeholder engagement, such as Task Force meetings, MPO Board meetings, and virtual municipal roundtables.

The systemic safety analysis subtask will build upon these findings and may identify additional Emphasis Areas for the Vision Zero Action Plan. That task will identify specific factors that may be overrepresented across the region and highlight the most common roadway safety challenges in each subregion by characteristics of crash, roadway types, and contributing factors to crashes. The systemic safety task will also draw upon key takeaways and safety challenges identified by state and local government stakeholders and the public. Existing conditions will help inform the development of MPO Subregion safety profiles that describe the common infrastructure, behavioral, operational, and modal safety problems in the region. By combining existing conditions, the High Injury Network (HIN) and high-risk networks, and stakeholder and public engagement findings, a prioritized list of locations will be identified for consideration in the strategy and project selection task.

Strategies will span roadway design, policy and process changes, education and stakeholder coordination, and emergency response recommendations to address the top identified safety challenges. The existing conditions analysis will directly feed into the prioritization of policy recommendations, and changes or improvements that municipalities, the MPO, and the Commonwealth can pursue to support roadway safety. The data analysis can also inform the development of location-specific projects, as well as region-wide systemic solutions to address the region’s top safety problems.