Tag: data

Collecting the wrong information doesn’t help us plan well

June 13, 2011 / / 0 Comments

The Illinois Traffic Crash Report (see scan below) has a field in the upper left titled “PEDV” which means “Pedalcyclist or pedestrian visibility.”

The possible entries for this field are the following codes*:

  1. No contrasting clothing
  2. Contrasting clothing
  3. Reflective material
  4. Other light source used

For my crash report, the police officer noted “1 – No contrasting clothing.” I don’t remember what I was wearing that night, so I can’t dispute that. I didn’t have lighting required by state law. I don’t know if the police officer would mark “4 – Other light source used” if I did. I’m not aware of what kind of guidance the report or data dictionary offers the police officer filling out the report; how is “contrasting clothing” defined?

Wearing contrasting clothing is not required by law. Using a headlight while bicycling at “nighttime” is. The light will be more effective than any kind of clothing in increasing the visibility of the bicyclist.

The crash report should note the bicyclist’s compliance with state law, not whether or not their clothing choice may have been a contributing factor in the crash (which the presence of this code on the report implies). I took the photo below last night when I was wearing a black jacket and gray jeans. It doesn’t appear very contrasting – but I was in compliant with state and city laws about lighting at night.

My clothes may blend into the night, by my blinking light surely doesn’t.

Collecting information on lighting law compliance could help cities and police better plan education and enforcement initiatives. It can give us information on crashes that we wouldn’t otherwise have, like how many crashes involved cyclists who didn’t have the required lights. Or where a lot of crashes occur even though a high percentage of cyclists involved there had sufficient lighting.

Illinois cyclists had a big win with the inclusion of doorings in state-provided crash reports. I think the next change should be to record information on compliance with lighting laws. If you need a good light, try this one from Planet Bike.

*This information comes from the “2004-present person codes” data dictionary from the Illinois Department of Transportation.

New site brings together bike crash maps and projects

May 5, 2011 / / 0 Comments

I just finished creating a website that brings together my original Chicago bike crash map and all of its offshoots created by others. It also includes a more details and updated FAQ page as well as a short history of how the map and data came to be.

Enter the Crash Portal.

Right now it features projects from myself, Francesco Villa, Derek Eder, and George Aye’s students at the School of the Art Institute “Living in a Smart City” class. The site also links to my inspiration: Boston and San Francisco. If you have a related project, email me and I’ll figure out a way to add it to the site.

Screenshot of new Crash Portal

My television interview about dooring data

April 28, 2011 / / 0 Comments

Last week you heard me on WGN 720 AM talk about bicycling in Chicago and my bike crash map.

This week you’ll get to see me talk about bike crash and dooring data on WTTW’s Chicago Tonight program. It comes after a rule change announced on Sunday: the Illinois Department of Transportation will begin collecting crash reports for doorings. Previously, these were “unreportable.”

WTTW reporter Ash-har Quraishi came over to my house Thursday to ask me about what kind of information the crash data I obtained from IDOT includes and excludes.

Initial intersection crash analysis for Milwaukee Avenue

April 25, 2011 / / 0 Comments
Slightly upgraded Chicago Crash Browser

This screenshot from the Chicago Crash Browser map shows the location of bike-car collisions at Ogden/Milwaukee, an intersection that exemplifies the yellow trap problem the city hasn’t remedied.

List of the most crash-prone intersections on Milwaukee Avenue in Chicago. Using data from 2007-2009, when reported to the Chicago Police Department. Dooring data not included on the bike crash map. I used QGIS to draw a 50-feet buffer around the point where the intersection center lines meet.

Intersecting street (class 4*) Bike crashes
Chicago Avenue (see Ogden below) 12 (17)
California Avenue 9
Halsted Street & Grand Avenue 7
Damen Avenue & North Avenue 6
Western Avenue 6
Ogden Avenue (see Chicago above) 5 (17)
Ashland Avenue 5
Diversey Avenue 5
Fullerton Avenue 5
Elston Avenue 5
Augusta Boulevard (not class 4) 5

Combine the six-way (with center triangle) intersection of Ogden, Milwaukee, Chicago, and you see 17 crashes. Add the 6 just outside the 50-feet buffer and you get 23 crashes. Compare this to the six-way (without center triangle) at Halsted, Milwaukee, Grand, where there’s only 7 crashes.

What about the two intersections causes such a difference in crashes? Let’s look at some data:

Ogden, Milwaukee, Chicago Halsted, Milwaukee, Grand
Automobile traffic Approx 58,000 cars per day Approx 50,000 cars per day.
Bicycle traffic Not counted, but probably fewer than 3,100 bikes More than 3,100 bikes per day*
Bus traffic Two bus routes Three bus routes
Intersection style Island; three signal cycles No island; one signal cycle

*Notes

Traffic counts are assumed estimates. Counts are taken on a single day, either Tuesday, Wednesday, or Thursday. Bike counts at Halsted/Milwaukee/Grand were actually taken on Milwaukee several hundred feet northwest of the intersection so DO NOT include people biking on Halsted or Grand! This means that more than 3,100 people are biking through the intersection each day.

Intersection style tells us which kind of six-way intersection it is. At island styles you’ll find a concrete traffic island separating the three streets. You’ll also find three signal cycles because there are actually three intersections instead of one, making it a 12-way intersection. Also at these intersections you’ll see confusing instructional signage like, “OBEY YOUR SIGNAL ONLY” and “ONCOMING TRAFFIC HAS LONGER GREEN.”

These intersections are more likely to have a “yellow trap” – Ogden/Milwaukee definitely has this problem. The yellow trap occurs at that intersections when northbound, left-turning motorists (from Milwaukee to Ogden) get a red light but they still need to vacate the intersection. Thinking that oncoming traffic has a red light but are just being jerks and blowing the red light (when in fact they still have a green for 5-10 more seconds) they turn and sometimes hit the southbound traffic. The City of Chicago acknowledged this problem, for bicyclists especially, in summer 2013 but as of November 2014 the issue remains.

Here’s a more lengthy description of one of the problems here as well as an extremely simple solution: install a left-turn arrow for northbound Milwaukee Avenue. The entire intersection is within Alderman Burnett’s Ward 27.

Source and method

I can’t yet tell you how I obtained this data or created the map. I’m still working out the specifics in my procedures log. It involved some manual work at the end because in the resulting table that counted the number of crashes per intersection, every intersection was repeated, but the street names were in opposite columns.

Crash data from the Illinois Department of Transportation. Street data from the City of Chicago. Intersection data created with fTools in QGIS. To save time in this initial analysis, I only considered Milwaukee Avenue intersections with streets in the City of Chicago centerline file with a labeled CLASS of 1, 2, or 3.

Illinois will finally begin tracking dooring bike crashes

April 24, 2011 / / 0 Comments

Governor Quinn made a rule change today requiring Illinois police departments to record dooring-type bicycle crashes on the SR-1050 motorist crash reporting form, according to Jon Hilkevitch of the Chicago Tribune. The announcement will be made tomorrow.

Apparently, Gov. Quinn read the Chicago Tribune’s article on March 21st about how the Illinois Department of Transportation could not and would not collect information on dooring crashes. I first wrote about this data deficiency on March 11.

For now, responding police officers will have to write DOORING next to the bicyclist’s name on the crash reporting form (the Chicago Police method was to write DOORING on a second piece of paper and record this data internally – IDOT would not accept the second page). The Tribune article explains that IDOT already ordered a bunch of new forms and won’t make a new order until 2013 at which time the form will have a checkbox making this process much simpler.

I would like to thank Governor Quinn, writer Jon Hilkevitch, Amanda Woodall, the Active Transportation Alliance, and all who contacted IDOT asking for their reporting standards to be changed to record dooring crashes. This means that next year you’ll see bike crash maps with a ton more dots – those of doorings, unless we continue educating ourselves, family and friends about riding AWAY from the door zone.

Why collecting this data is important

From the article:

[Active Transportation] Alliance officials said dooring accidents are common, basing the conclusion on reports from bicyclists. But without a standardized statewide reporting system, there has been no way to accurately quantify the problem or pinpoint locations where such accidents frequently occur and where modifications to street layouts would help, alliance officials said.

“We hope to use the data to obtain funding for education safety so drivers as well as bicyclists know what the risks are and what the factors are to create safer roadways,” said Dan Persky, director of education at the alliance.

Ride out of the door zone. Illustration by Gary Kavanagh.