Pedestrian and Cyclist Safety in Detroit: Part Two

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In part one of this series we discovered where pedestrian- and cyclist-involved crashes are happening, determined a high injury network for pedestrians and cyclists, and compared those to traffic volumes, points of interest, and cycling infrastructure. In part two we’re digging into the characteristics of the crashes: who is involved, when the crashes happen, and what types of injuries result.

This being part two, the phrase “combined pedestrian- and cyclist-involved crashes” is tedious to write, anytime the word “crashes” is used, assume it means that a driver was involved in a crash with a pedestrian and/or a cyclist.

While crashes happen throughout the year, warmer months have more, as do Fridays, afternoons and evenings. The pedestrian or cyclist is most likely to be between 20 and 29 years old, and be traveling on a major collector road that’s bigger than a residential street, but usually fewer than four lanes. Injuries in general are declining, and crashes without injury or possible injury are slightly more likely than those with a confirmed injury.

Let’s dig in.

In regards to when these crashes are happening, the highest amount of crashes from 2017-2021 are in August. Overall, pedestrian-involved crashes remain relatively consistent throughout the year, ranging from 148 in February to 240 in September, and an annual median of 192. Cyclist-involved crashes have a broader range, from 17 in February to 124 in August, and an annual median of 53.5 crashes.

Wednesday and Friday have the highest amount of cyclist-involved crashes from 2017-2021. For pedestrian-involved crashes, Friday and Saturday (355) have the highest amounts. Without daily volume for cyclists and pedestrians, we can’t determine whether these days also have the highest amount of crashes relative to volume which would make them the most dangerous, we can only say that these days have the highest amounts.

As for the time of day, the second half of the day has more total crashes (2,179) than the first half of the day (817), with the most crashes happening between the hours of 3 pm and 9:59 pm. There is a large jump in the total crashes during the 7 am hour from the 6 am hour, a 169.2% increase from 39 to 105 crashes.

The age bracket with the highest number of crashes both as cyclists and pedestrians is 20-29, with 19.1% of all crashes. This is higher than the 13.9% of the Detroit population that this age group makes up, though we don’t know what percentage of the cyclist/pedestrian volume this age group makes up. The second most crashes from 2017-2021 are in the 50-59 age group, with 18.0% of crashes but only 11.8% of the population.

Click the two arrows >> in the top right corner of the map to hide or show the legend. The icon right below the legend icon with the stacked squares gives you access to turn different layers on and off.

Most census tracts in Detroit are either Black or African American majority (green) or Hispanic or Latino majority (blue). Fifteen percent  (459) of the total crashes (3,065) between 2017-2021 involved minors, with 332 pedestrians and 127 cyclists crashes. We can see the locations of the crashes in the map above, generally distributed across the city, with some clusters in Southwest, on the far west side, upper west side, far east side, and downtown-midtown. This map also includes census tract population with 2016-2020 ACS 5-year estimate for predominant race/ethnicity. Important to note, this is just an indication of the predominant race/ethnicity of the population of those tracts, not necessarily race/ethnicity of the pedestrians and cyclists involved in these crashes. The nature of these crashes indicates that they happen on trips near where someone lives, but that information is not in this data. In the current data, the race of the people involved in crashes is only included for the year 2021. Race data sourced from the crash reports of the incident is documented by the reporting officer, which may differ from the self-identified race of the people involved, and to respect the agency of those involved, we have not included that information. For more, please read our blog post Data Isn’t Colorblind where we discuss the recognition that any and all data is collected through a process which can have built-in biases, structural inequities, and other confounding factors, all of which impact the resulting data we use to make decisions in the world.

For some context, further back in Detroit’s history in 1970, the Detroit Geographic Expedition and Institute (DGEI) created a map showing the patterns of “Children’s Pedestrian Deaths & Injuries by Automobiles.” On this map there are concentrations of deaths and injuries by automobiles on the lower eastside, near westside. This map also has lines denoting areas of majority black or white population, and it appears that most of the crashes are happening in areas with majority black population.

The DGEI also created a map of where accidents involving Black children were happening along the east-west commuter routes between the wealthier, majority white cities to the east of Detroit (Grosse Pointe Park, Grosse Pointe, Grosse Pointe Farms, Grosse Pointe Woods, and Grosse Pointe Shores) and downtown, the economic center of Detroit.

When we add in the 2021 traffic volume to the 2017-2021 pedestrian- and cyclist-involved crashes for people under 18 years old, we don’t see concentrations along the same east-west streets as the DGEI maps, nor high volume traffic areas. The lack of crashes along commuter routes likely correlates to commuter route changes since 1970. In the map below of inflow commuters to Detroit in 2016 produced by SEMCOG, there are more commuters coming from communities with a darker blue, and the Pointes are light relative to communities to the north and west of Detroit.

These crashes happen all across the city, on all types of roads. The four main functional classifications in Detroit are (1) local roads like typical residential streets; (2) minor and (3) major arterials that provide the fastest level of travel, and are meant to move traffic quickly across the city and in and out of the city (Livernois and Warren are examples of minor arterials, Gratiot and Grand River are examples of major arterials); lastly, (4) major collectors—such as Central and Puritan—are roads that connect arterials to local roads. The amount of crashes is roughly evenly distributed between the types of roads, from 20.6% on major arterials to 27.3% on major collectors. However, since there are many more miles of local roads (~2,178 miles) than major arterial roads (~381 miles), this means there are far more crashes per mile on major arterials than local roads.

With the different classifications of roads and different paces of travel, lanes to cross, volume, and infrastructure, the types of injuries sustained by pedestrians and cyclists vary. The five types are coded by the responding officer, and usually have a letter association that we removed in the visualizations for clarity.
K – Fatal Injury: Any injury which results in death
A – Suspected Serious Injury: Any injury other than fatal which prevents normal activities and generally requires hospitalization
B – Suspected Minor Injury: Any minor injury that is evident to others at the scene
C – Possible Injury: Any possible injury that is reported or claimed
O – No Injury: No indication of injury
(For a more detailed explanation of these injury types, refer to page 58 the Michigan State Police UD-10 Traffic Crash Report Instruction Manual.)
As noted by the callouts on the chart, crashes on local streets have the highest rates of no injury or possible injury on crash reports, while crashes on minor arterials have the highest rates of fatalities, with major arterials close behind.

Injuries for pedestrians and cyclists also vary between road classifications. Major collectors have the most cyclist-involved crashes, and the highest amount of incapacitating injuries. For pedestrian-involved crashes, local roads and major collectors have the highest amounts, but minor and major arterials have the most fatalities.

Crashes of all injury types have fluctuated over the last five years, though crashes with possible injuries recorded have dropped nearly in half from their recent highs, though fatalities and incapacitating injuries have remained relatively stable.

Crash rates for cyclists and pedestrians differ in prevalence. As of 2021, no injury and possible injury are most common for cyclists, but possible injury and non-incapacitating injury are most common for pedestrians. Also for pedestrians, crashes with possible injury have dropped the most from 2017 to 2021, while fatalities have increased from 33 to 46 in that span. For cyclists, crashes resulting in all injury types have either stayed near the same or decreased, again with possible injury dropping the most, and only fatalities increasing, by one from zero.

More to learn

As the City of Detroit works towards its goal of “eliminating fatal and serious injury crashes” by 2050, the Comprehensive Safety Action Plan Steering and Implementation Committee will be publishing annual reports of their progress. To draw firm conclusions on pedestrian and cyclist safety progress in Detroit, we need more data. In particular, vehicle traffic, cyclist, and pedestrian volumes over time would be critical in determining whether safety has increased as the city puts more effort into multi-modal transportation infrastructure. Additionally, locations of cycling infrastructure and usage over time would inform whether that infrastructure has created safer conditions for people not in vehicles. The City has an ongoing program to increase the amount of speed bump installations throughout the city, some with pass-throughs for cyclists and some without, an analysis of whether different types of speed bumps have an impact on pedestrian and cyclist safety would be interesting. The City’s Department of Public Works and Traffic Engineering Divisions are partners with the statewide Safe Routes to School Program, but there aren’t currently any maps available to do an analysis of the impact of these routes on the safety of young people and others on those routes.

If you haven’t read part one that focuses more on geography, you can read that here.

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