When do cyclists crash?

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Chart 1. The chart above shows the hourly activity of aggregated reported crashes in Illinois in 2010. It shows the hour of the day, that, throughout the year, saw the most injuries and fatalities. 

This post is fourth in a series on crash data sponsored by Jim Freeman, a Chicago lawyer specializing in pedestrian and bicycle crashes. Read the other posts in this series.

The League of Illinois Bicyclists (LIB) recently posted a link on its Facebook page to an event in August called “Designing for Bicycle Safety”, hosted by the Chicago Metropolitan Agency for Planning (CMAP). A person commented,

We can design for bike safety until we are blue in the face, but unless bicyclists come to their senses and buy lights and reflective clothing for riding after dark – there will continue to be needless rider deaths and incapacitating injuries. I believe this needs to be top priority in rider awareness education.

Safer infrastructure should be the top priority in all things bicycling, and when it comes to reducing crashes at night, we agree that encouraging cyclists to use lights at night is important (Get Lit!). I wanted to know just how many crashes occur at each hour of the day. As is usual when it comes to bike crash data crunching, it takes longer than I originally thought or planned to get the full answer. In essence, though, the majority of crashes and injuries occur during “evening rush hour” while the majority of fatalities, while very small, occurred at night.

Update July 27, 2012: New, interactive charts show the same data in different waysContinue reading When do cyclists crash?

Cyclists in Chicago crash less often than those in the suburbs

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This post is third in a series on crash data sponsored by Jim Freeman, a Chicago lawyer specializing in pedestrian and bicycle crashes. Read the other posts in this series

I recently came across an undated and unattributed article on an injury lawyer’s website about bike crashes. The website is designed to capture as many keyword searches about bike accidents and injuries as possible, and likely shares some its content with other injury lawyer websites around the country.

The article is titled Is bicycling in Chicago more dangerous than in surrounding Illinois counties?. Its URL gave away the publishing date as June 2012. I read the article and I decided to verify one of the claims made there:

Looking at 2010 data collected from all counties vs. Chicago, Illinois collar county bike riders were actually more likely than riders in Chicago to be involved in either fatal or incapacitating bike accident!

It’s true. At least based on the data that is collected.

Here’s some background on the kind of data that is collected: Every 10 years, the Census Bureau conducts the decennial census and asks the entire population in the United States to list the transportation mode they typically used  to get to work in the previous week for the longest distance. Every year (starting in 2005), the Census Bureau asks the same question but for a smaller portion of the population in the American Community Survey (ACS). The intention of ACS is to replace the decennial census to give researchers the same quality and breadth of data every 5 years instead of 10.

Aside from the shortcomings in the data based on that question (typical mode to work for the longest distance), it doesn’t count what modes people use to get everywhere else. The Travel Tracker Survey tells us that households in Cook County make an average of 9.1 trips per day (and the average household in Cook County has 2.6 people) – that’s 3.5 trips per day, and not all of them are to and from work.

Data that could better show the likelihood of getting into a crash is “bicycle miles traveled”. This measurement would ignore trip purpose and destination and simply tell how often people are cycling in the streets, exposed to the possibility of being involved in a crash with an automobile. Another useful measurement would be “ridership”, that is, how many people are cycling each day for any trip purpose. We’ve discussed how Chicago currently counts people riding bikes.

Without those data, though, planners rely on commuting data as a proxy for the number of people outside on a bike each day (well, each weekday). Below is verification of the claim that people outside Chicago and outside Cook County have a higher probability of being in a crash.

For every 1,000 people counted by the ACS who commuted to work by bicycle, the following number of people were involved in a crash in 2010 in which they received an incapacitating injury or died:

  • Chicago: 10.68 people
  • Cook County, including Chicago: 11.92
  • Cook County, excluding Chicago: 15.27
  • Collar counties*: 21.10

The same trend is present when looking at receiving any kind of injury from a bicycle crash with an automobile: those in Chicago are less likely to experience an injury than those in surrounding counties.

For every 1,000 people counted by the ACS who commuted to work by bicycle, the following number of people were involved in a crash in 2010 in which they received an injury:

  • Chicago: 109.96 people
  • Cook County, including Chicago: 116.12
  • Cook County, excluding Chicago: 132.73
  • Collar counties: 126.38

Download the spreadsheet I created to calculate these figures (.xls).

The spreadsheet contains other data, including density, average number of vehicles available per household (as you might guess, Chicago has the lowest number of vehicles available per household), mode share of bike commuting, and population. The low likelihood of crashing while bicycling in Chicago appears to be correlated with the city’s higher mode share of bike commuting, but also seems related to its population density and the lower number of vehicles available per household. There is safety in numbers.

* The collar counties are DuPage, Kane, Kendall, Lake, McHenry, and Will. These are the counties in the Chicago Metropolitan Agency for Planning (CMAP) research area.

N.B. All data here are estimates from a sample of the population and are subject to error margins. All demographic data is collected in the 2008-2010 3-year American Community Survey, and downloaded from either CMAP’s website (transportation modes, household size, vehicle availability), or the American FactFinder. Crash data is only from 2010, from the Illinois Department of Transportation (IDOT).

Photo shows people cycling in Blue Island, Illinois, adjacent to the southern border of Chicago. Photo contributed to our Flickr group by Jane Healy.

Fatality tracker update: four transit deaths, and 80% of pedestrian deaths this year are hit-and-run crashes

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The driver involved in the death of Martha Gonzales at 17th Place and Halsted Street has never been found. Quickly following the incident, Alderman Solis and the Chicago Department of Transportation implemented a few design interventions, including refreshed crosswalk markings, and a leading pedestrian interval that gets pedestrians crossing the street before drivers can start making turns. 

This is the second in a five part series on crash data analysis sponsored by Lawyer Jim Freeman.

2012 fatality stats*:
Pedestrian: 6 (5 have been from hit-and-run crashes)
Pedalcyclist: 0
Transit: 4

I made the Fatality Tracker because I want (need) to demonstrate that our roads are needlessly deadly. I’m not writing this to talk about how they may be dangerous. I don’t feel I can qualify or define that in a way that we’d all accept. So I’ll deal purely with specifics: how many people perished because our culture has an acceptable frequency of traffic deaths.

We report only deaths because of walking, cycling, or using transit. Why? Frankly, because tracking all traffic-related deaths would be too difficult to monitor accurately. I rely on newspaper reports, which don’t list all traffic deaths. If they were reported, the Fatality Tracker would be updated every 1-3 days.  Continue reading Fatality tracker update: four transit deaths, and 80% of pedestrian deaths this year are hit-and-run crashes

What is the outcome of hit-and-run crashes?

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This is the first in a five part series on crash data analysis sponsored by Lawyer Jim Freeman.

Pedestrians and bicyclists involved in hit-and-run traffic crashes with automobiles in Chicago receive more injuries and die more often than pedestrians and bicyclists involved in hit-no-run crashes while drivers and passengers have the opposite outcome. This post attempts to describe the situation of hit-and-run crashes in Chicago.

On Sunday I wrote that 75% of all pedestrian traffic deaths this year were in hit-and-run crashes; it’s important to know that all the offending drivers were later apprehended (note 1). The horrific events on Saturday made me curious: How prevalent are hit and run crashes? I already know that our hit-and-run rate is 28.5% for 2005-2010, but how does that translate into frequency of injuries and fatalities? Are hit-and-run crashes worse for drivers, passengers, pedestrians, and cyclists? Better than hit-no-run crashes? I ran a few calculations to find the answers. I came up with more questions than answers, but my initial interpretation is that hit-and-run crashes are not much better or worse than hit-no-run crashes when looking at every crash participant combined. Continue reading What is the outcome of hit-and-run crashes?