Taghousehold travel survey

Divvy overtime fees and most frequent trip distances

Two people check out a Divvy bike in front of 3565 N Pine Grove Avenue, home to residents who sued the Chicago Department of Transportation and Alderman James Cappleman to have its installation prevented. That failed. Photo by John Greenfield. 

Kaitlyn Jakola interviewed me last week for the Chicago Magazine blog, The 312, about how newcomers should deal with Divvy bike sharing. I think I gave some good answers. Stick to the bike lanes by using an app (although that’s hard because so many of them don’t link up) and think about the rules you would follow if you were driving a car (which assumes you know how to do that). Two of the commenters called this a scam. The first stopped there but the second commenter showed some understanding of transportation and economics so I thought that I could reply and it would be taken seriously. They said:

It seems to me like the system is designed to create extra or ‘overage’ fees. Having to stop every 30 minutes and ‘redock’ your bike is prelude to a ripoff. By the time you get comfortable riding and determine where you’re going to go, it’s time to ‘redock’ then…

It doesn’t seem like the commenter knows how bike sharing works: think of a taxi that you drive yourself. The bike taxis are available at predetermined stands around the city. It’s there when you need it and you don’t need to own the vehicle.

Regarding overtime fees… The average trip taken on Divvy bikes is only 18 minutes long, which the Chicago Tribune – part of the same parent company as Chicago Magazine – reported on. That coincides with the average trip distances Americans and Cook County residents take. The Southern California Association of Governments, the federally-designated Metropolitan Planning Organization for the nation’s largest regional planning area, found that 80% of trips residents in that region were less than 2 miles long (.pdf). This matches what the Chicago Metropolitan Agency for Planning, the local MPO, found for Cook County that the average trip distance was 3.0 miles and the median trip distance was 2.3 miles (.pdf). Both studies’ figures aggregate trip mode, so this includes all trips people make by bus, personal automobile, walking, or bicycling. All of the distances are bikeable in 18 minutes.

Mode share by trip miles and trip frequency in Chicago and Cook County

Two tables in this post. Data from the Chicago Metropolitan Agency for Planning’s 2008 Travel Tracker Survey. Download source file (pdf).

Table 1. Number represents share of trip miles taken by that mode. So in Central Chicago (which seems to comprise neighborhoods as far north as Uptown and as far south as Hyde Park), 1.4% of all trip miles are by bike. If 1,000 people take 100 trips of 2 miles each, then 2,800 miles will be by bike.

[table “1” not found /]

Table 2. Number represents share of trips taken by that mode, regardless of distance.

[table “2” not found /]

How high (and low) expectations can make traffic safer

I have low expectations of fellow Chicagoans who are moving their vehicles on the same roads I cycle on. I expect that every door will fling open in my path, causing me to be doored. I also expect to be cut off at any moment, and especially in certain places like at intersections (where the majority of crashes occur), bus stops, or in places with lots of parallel parking activity. Because of these expectations I feel that my journeys have been pretty safe. My low expectations cause me to ride slower, ride out of the door zone, and pay attention to everyone’s maneuvers.

This is another post inspired by Traffic: Why we drive the way we do (and what it says about us) by Tom Vanderbilt. From page 227 of “Traffic”, about expectations :

Max Hall, a physics teacher in Massachusetts who often rides his collection of classic Vespas and Lambrettas in Rome, says that he finds it safer to ride in Rome than in Boston. Not only are American drivers unfamiliar with scooters, he maintains, but they resent being passed by them: “In Rome car and truck divers ‘know’ they are expect not to make sudden moves in traffic for fear of surprising, and hurting, two-wheeler drivers. And two-wheeler drivers drive, by and large, expecting not to be cut off.”

The scooter drivers have high expectations, and it seems that they’re being met.

This all plays nicely with the “safety in numbers” theory about cycling: the more people who are riding bicycles, the more visible bicycling is, and the more aware a driver will be around people who are bicycling, and the more they will expect someone on a bicycle. Awareness means caution.

It’s difficult to gauge the safety of cycling in Chicago as we’ve no exposure rate: we don’t know how many people are cycling how many miles (nor where).

A cyclist waits for the light to change at Milwaukee Avenue and Ashland Avenue. 

Exposure rate

Exposure rate in the sense I’m using it here means the number of times someone is in a crash or injury for each mile they ride. We know how many crashes and injuries are reported each year (in the Illinois Motorist Crash reports), but we don’t know how many miles people ride (neither individually nor an estimated average).

There was a limited household survey of Cook County residents in 2008 from CMAP, called Travel Tracker, that collected trip distance information for all trips members of a household made on all trip modes – I haven’t looked into this yet.

It would be highly useful if the Chicago Department of Transportation conducted ridership counts at the 10 intersections with the highest crash rates. And if the 10 intersections changed the following year, the new intersections would just be added to the initial 10 to track the changes of the initial 10. This would be one step closer to being able to determine a “crash rate” for each intersection.

© 2014 Steven Can Plan

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