Tag: crash reporting

Just how many taxi vs. bicycle crashes are there? A Google Refine story

April 26, 2011 / / 0 Comments

On this Chicagoist story about how IDOT will now collect data on doorings (instead of ignoring that crash type as they preferred), I opened the story photo entitled “Cabbie takes down another” by Moe Martinez. His photo caption reads, “you see it alot … thankfully this guy seemed to be relatively ok … coherent and what not.”

I wanted to know just how often “we” see taxi drivers crashing with people riding bicycles. You can’t filter by vehicle type in either mine or Derek’s bike crash maps, but you can via the Fusion Table.

I decided to get the answer via Google Refine and make a screencast to show you just how quick and powerful a tool it is.

It’s dead simple:

  1. Load a CSV of the data into Google Refine.
  2. Click on the VEH1_SPECL column’s down arrow, then Facet>Text Facet.
  3. In the facet box, sorted alphabetically, find “TAXI/FORE HIRE.”
  4. The number of rows that apply is listed: 353.
  5. Divide 353 by the total number of rows, 4931, multiply by 100, and you get your percentage.

Taxi drivers are involved in just 7.2% of bicycle crashes in Chicago in 2007-2009.

The majority of crashes, at 66%, involve people driving “PERSONAL” vehicles. And 80% of those crashes are with a passenger vehicle that’s not a van, minivan, SUV, truck, or bus (so probably a sedan or coupe). Let’s look at more data.

How many taxis are there and how many personal vehicles are there? Are taxicabs involved in a disproportionately higher number of crashes?

About 781,023 people drive to work, either alone or with someone else, in Chicago (data from 2005-2009 5-year American Community Survey). 1,063,047 households have 1,218,594+ vehicles available in Chicago. Let’s assume the 7,000 taxicabs in Chicago are not counted as a “vehicle available.”* That’s 1,225,594 “personal” vehicles. If all were on the road at the same time, only 0.57% of them would be taxicabs. But they’re not on the road at the same time. So let’s take that number of people who drive to work and add 7,000 vehicles to it. So of those 788,023 “vehicles” now on the road, just 0.88% of them are taxicabs.

So it does seem that taxicabs are involved in a disproportionate number of crashes when compared to their presence on the streets. However, taxicabs are most likely driven more more miles and for more time than personal vehicles thus making their exposure to people bicycling greater than drivers of other vehicles. (A majority of “personal” trips are very short.)

New data coming soon

I can’t wait to get the 2010 crash data. Here’s why: In 2007, students in a taxi driver training course at Harold Washington College received some education about sharing the road with bicyclists:

A pilot “Share The Road” education module was launched at the taxi training school at Harold Washington College. It includes a 25-30 minute lecture, with discussion. After the pilot, the class will be required for all people training to drive taxis in Chicago. In the future, bicycle questions will be included on the exams required to become taxi drivers. June 2007 MBAC meeting minutes (PDF).

The number of crashes between taxi drivers and people riding bikes jumped from 2007 to 2008, but declined heavily between 2008 and 2009. More data will show us a clearer trend that may lend insight into the impact of the “Share The Road” education module.

*Notes

The question (PDF) on the American Community Survey asks, “How many automobiles, vans, and trucks of one-ton capacity or less are kept at home for use by members of this household?” This may or may not include taxicabs stored at home.

I don’t know how many taxicabs there are in Chicago, but the Chicago Sun-Times reported there are approximately 7,000.

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.

You may have heard me on the radio this morning in Chicago

April 21, 2011 / / 0 Comments

Here’s the audio clip of my interview with WGN 720 AM producer Rob Hart about biking in Chicago and the bike crash map I made. It aired this morning – I had no idea until someone left me a comment on a Flickr photo that they heard me.

Listen now: Steven Vance on biking and bike crashes in Chicago on WGN.mp3 (will play in your browser).

I am too nervous to listen to this. I’m sure I said something wrong or misspoke.

Biking in Chicago is fun and you should do it. You don’t need special gear or equipment and you can buy a cheap bike at Working Bikes in Pilsen, at 2434 S Western Avenue.

Transcript

[ding, ding]

A little bell may be what comes to mind when you think of riding your bike, but the reality is more like this.

[sounds of traffic]

A busy street full of cars, trucks, and buses. With drivers who are looking at something else.

Me: There’s a lot of driveways. A lot of drivers are making right and left turns and if you ride too close to the curb they will probably not see you, so you have to ride sometimes outside the bike lane if you want to be noticed.

Steven Vance ditched his car 5 years ago. He rides his bike all over the city and he says sometimes it’s a white knuckled experience.

Me: It can be. It does take a little bit of resolve. Sometimes your nerves will get frayed, but I think the benefit outweighs the cost.

After a newspaper [Bay Citizen] in San Francisco mapped out bike crashes on its website, Vance decided to plot bike crashes in the Chicago area on his.

Me: I saw that, and I thought, “You know what, I think I can do that.” I asked the Illinois Department of Transportation for the data and they promptly sent it over and I, as quickly as possible, put it online.

The diagonal streets are the worst, he found, and that includes Milwaukee Avenue.

Me: You could find Milwaukee just by the number of dots representing the crashes. You didn’t need a label to say that this was Milwaukee Avenue. You could tell simply by the string, the constant string of dots.

 

Two new beta apps for Chicago geography

April 12, 2011 / / 0 Comments

I think 2011 is going to be the year of apps for me. I developed one for bikes and one for politics.

Bikes

I made the “Chicago Bike Data Portal” app on Saturday night. It gets your location via the HTML5 geolocation API and loads a list and map of all the reported bike crashes within half a mile. It works on some mobile phones, too (at least Android and iOS). Expect to see more data in the future, like ped and automobile crashes.

Politics

Then on Monday I made an app called, “Who is my Chicago Alderman?” where people can type in their address (or any address) and retrieve the alderman’s name, addresses, and phone numbers. I’ve already identified a problem where the app returns the wrong information for an address. I think this is a problem with the geocoder. Ever since CivicFootprint (a project of Center for Neighborhood Technology) disappeared, the city’s been missing an easy-to-use app for finding alderman. The city clerk’s website takes too long to use and is not as informative.

Other apps I built or worked on