TagGoogle Refine

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

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.

Using Google Refine to get the stories out of your data

Let’s say you’re perusing the 309,425 crash reports for automobile crashes in Chicago from 2007 to 2009 and you want to know a few things quickly.

Like how many REAR END crashes there were in January 2007 that had more than 1 injury in the report. With Google Refine, you could do that in about 60 seconds. You just need to know which “facets” to setup.

By the way, there are 90 crash reports meeting those criteria. Look at the screenshot below for how to set that up.

Facets to choose to filter the data

  1. Get your January facet
  2. Add your 2007 facet
  3. Select the collision type of “REAR END” facet
  4. Choose to include all the reports where injury is greater than 1 (click “include” next to each number higher than 1)

After we do this, we can quickly create a map using another Google tool, Fusion Tables.

Make a map

  1. Click Export… and select “Comma-separated value.” The file will download. (Make sure your latitude and longitude columns are called latitude and longitude instead of XCOORD and YCOORD or sometimes Fusion Tables will choke on the location and try to geocode your records, which is redundant.)
  2. Go to Google Fusion Tables and click New Table>Import Table and select your file.
  3. Give the new table a descriptive title, like “January 2007 rear end crashes with more than 1 injury”
  4. In the table view, click Visualize>Map.
  5. BAM!

I completed all the tasks on this page in under 5 minutes and then spent 5 more minutes writing this blog. “The power of Google.”

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