American Community Survey

A quick look at bicycling in Evanston

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The City of Evanston was recently awarded, for the first time, a Bicycle Friendly Community (Silver) designation by the League of American Bicyclists, based on its application (see the full list of awardees, .pdf). For reference, the City of Chicago has a Silver designation. Applications must be renewed with the organization every 5 years. The application asks questions like “How many government employees (including the Bicycle Program Manager), expressed in full-time equivalents, work on bicycle issues in your community?” and “What are the primary reasons your community has invested in bicycling?” It also asks about the mileage of different types of bikeways the city has as well as the mileage of roads (to calculate a density).

I wanted to know more about bicycling in Evanston, so I looked at the American Community Survey’s “Commuting Characteristics by Sex” table to see how people go to work; I looked at the 2006-2010 5-year estimate which asks different people each year for 5 years and is a representation of the data collected in that time period, and not for a single year. The population size for this table is 36,745 workers aged 16 and older and they can work in or outside Evanston (62.4% work the boundary).

Bicycle

All: 2.6% ± 0.6. In Chicago, 1.1% ± 0.1
Men: 4.0% ± 0.9. In Chicago, 1.6%, ±0.1
Women: 1.2% ± 0.6. In Chicago, 0.6% ±0.1

The shares in Evanston are significantly greater, but so are their margins of error. This is likely because the sample size in Evanston is much smaller than Chicago (1,219,311 workers aged 16 and older).

Other modes

Transit: 19.5% ± 1.4
Drive alone: 51.9% ± 1.8
Carpooled: 6.5% ± 1.0
Walked: 11.2% ± 1.4

Chicago has a higher transit share (26.6% ± 0.3), slightly lower drive alone share (50.9% ± 0.3), higher carpool share (10.0% ± 0.2), but a much lower walking share (5.8% ± 0.2)

Statistics

Population: 73,880
Bike lanes: about 6.7 miles including the new Church Street cycle track
Lake shore path (not including every side path): about 2.2 miles*

The Active Transportation Alliance blog notes that the award will be presented to Evanston City Council on Monday, October 22, at 7 PM.

* This data comes from my personal geodatabase, which contains information I manually digitized from the Evanston city bike map (.pdf).

Update October 21, 2012: Chicago has a silver level designation, not gold.

Census releases commuting to work data for 2011: walking, biking, transit continue to rise

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A higher percentage of Chicagoans are walking to work. Photo by Joseph Dennis.

The Census Bureau has started releasing data from the 2011 American Community Survey. This survey is conducted annually and will collect every 5 years the same amount of data the decennial census collects every 10 years. So far, only 1-year estimate data is available. 1-year estimate data for a year should only be compared to any other year’s 1-year estimate data (3-year and 5-year estimates, with larger sample sizes, will be available by the end of the year). The table below shows commuting patterns for Chicago, from the S0801 table: Commuting characteristics by sex.

View this table in a High Chart from Derek Eder.

1-year estimates, ACS	2005	2006	2007	2008	2009	2010	2011	Notes
Workers	1,162,550	1,209,122	1,230,933	1,260,741	1,271,744	1,168,318	1,199,278	Major decline from 2009 to 2010.
Walking	5.5	5.4	5.4	5.8	5.9	6.5	6.3	Steady but slow increases.
Bicycling	0.7	0.9	1.1	1.0	1.1	1.3	1.4	Steady but slow increases.
Transit	25.3	25.4	26.7	26.7	26.5	26.5	27.6	Ups and downs.
Car, Drive Alone	53.4	52.6	51.2	50.5	50.8	50.2	49.9	Steady but slow decreases.
Carpool (2+ people)	10.7	10.7	10.4	10.3	9.9	9.4	9.0	Steady but slow decreases.
Taxi	1.6	1.5	1.4	1.4	1.5	1.5	1.5	Maintained.
Worked at home	2.9	3.6	3.7	4.2	4.2	4.7	4.3	Increases, then maintained.

I find it interesting that as “driving alone” decreased, the people who stopped driving alone didn’t necessarily switch to carpooling (where they could share the costs of driving), but switched to other modes of transportation.

It should be noted that the American Community Survey and the decennial census questionnaires ask the respondent to choose the longest distance mode they took to work, “typically”, for the week prior. This means that if you bike 1 mile to the train station and then take the train 10 miles to work, you should only select “transit”.

Follow up: Do 10% of bike commuters really crash each year?

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This is another data-intensive post. For the tl;dr version, read only the introduction and conclusion sections. Photo by Mike Travis.

Jeremy Gaines asked on the Chicaogist reblog of our Monday article (about Chicago cyclists crashing less often than those in the suburbs):

[Since we only have data about how often people bike for work purposes and crash data accounts for people who are biking for any purpose,] wouldn’t the large majority of total miles traveled be racked up those who commute regularly on bikes?

That’s a good question and I don’t know if there’s enough existing data to answer it. It came after the Chicagoist article and discussion board made it seem like bike commuters had a greater than 10% likelihood of being in a crash, and a 1% likelihood of dying or receiving an incapacitating injury (with chances greater in the suburbs). I replied that one could not make these assumptions based on the data available.

Gaines is a student at Northwestern University in Evanston. He doesn’t bike because he lives so close to everything he needs; when I inquired about his motivation to leave the comment, he replied: “I suppose a headline about bike safety caught my eye, even if it doesn’t apply to me. Plus biking, being green and efficient urban space usage, means that I support it, even if I don’t do it.”

The reason this question is important is because in my original article, I calculated the number of crashes per bicyclist (the crash rate) based on two different data sets, and the likelihood of being in a crash is most likely not 10%:

The crash data set doesn’t care about the crashed bicyclist’s trip purpose
The ridership data set cares only about trips to work

Let’s see if there’s more data we can work with to gauge bicyclist safety in the city.

Continue reading Follow up: Do 10% of bike commuters really crash each year?

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.

Interviews reveal what Chicago cyclists want

Happy New Year!

I’ll keep this one light as you focus on catching up on all the emails you missed over the holiday – or maybe you need a distraction (there’s comfort in stillness). We published every weekday through the holidays so take a minute to follow up on those articles (a list and summary at the bottom). But if you want to keep reading, this is what we have in store for you today: the Bike Fancy catalog of interviews.

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Jennifer and sons at Cortland Street and Paulina Street. Read their interview. Photo by Martha Williams.

I emailed Martha a while ago and suggested she use the rich data she had in the personal interviews she conducted with Chicago’s citizen cyclists. Data that can be used to help guide development of bikeway planning (similar to what the Streets for Cycling 2020 Plan is doing). So I gave her some tips on how to put it together and two days ago she published the results. Continue reading Interviews reveal what Chicago cyclists want

Cool Minneapolis bike features I’d love to see in Chicago

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The Midtown Greenway, a multi-use rails-to-trails conversion in a sunken railroad viaduct.

I recently spent a day in Minneapolis, Minnesota, visiting friends en route to Duluth for a bike trip along Lake Superior. Last year Bicycling magazine named Minneapolis the best U.S. city for biking (I guess they couldn’t keep giving the award to Portland, OR, every year) while Chicago dropped down to tenth place. So I was curious to see if the City of Lakes offers any lessons on ways to make cycling better here.

In fairness, the Twin Cities area has a few inherent qualities that have encouraged bike-friendliness. The combined population of the cities of Minneapolis and St. Paul is about 667,000, not much larger than Milwaukee and only a quarter the size of the city of Chicago. Minneapolis had ample available railroad right-of-way, which made it relatively easy to create a great network of urban off-street bike paths, 84 miles compared to Chicago’s 50. (We do have almost three times as many miles of streets with bike lanes.)*

Continue reading Cool Minneapolis bike features I’d love to see in Chicago