copyright 1996, Tracy-Williams Consulting
5 Bike program ideas in need of rethinking:
Things may not be as cut-and-dried as we might like
by John Williams
Make no mistake about it. The bicycle program
field still suffers from a youngster's growing pains. The answers haven't
all been written down in a book quite yet. But sometimes we act as if they
have. The foundations that support our work are often patched together assumptions,
best guesses, and sometimes unexamined prejudices. Lest we forget our roots,
here are five of the items we would do well to re-examine.
1. I've got the solution, now it's time to find the problem?
One way to come up with trivial results is to start with a solution in hand
and look for a problem it can solve. The idea is to only look at the problem
closely enough to justify our preconceptions and determine its usefulness
in furthering our agenda. A closer view may present a more complicated picture
and, as a result, a more complicated problem to solve. And a more complicated
problem may require a different solution.
As an example, one bike advocacy group decided that bike lanes were needed
in town. They did a Bike Lane Survey at popular alternative lifestyle hangouts,
asking people where they rode and if they would testify for bike lanes at
a public hearing. Of course, the survey results were positive. The group
next presented these results, along with a proposed map of their bike lane
network, to the city.
Will their proposal solve the problem? If the problem is "lack of bike
lanes" it surely will. After all, anyone can see there are no such
lanes on the streets they identified. However, are they really the answer
to anything else? Why knows. By starting off with their solution in hand,
they made it difficult to determine what real problems exist out there.
And without that information, any solution will be a shot in the dark.
2. The crash statistics prove our program is succeeding!
Crash statistics are notoriously unreliable indicators of success or failure.
This doesn't mean stats can't be useful in analyzing a problem or targeting
efforts. It simply means that collecting reliable bike crash data is very
difficult to do right and extremely easy to do wrong. Here are several recent
examples of misuse of crash data:
- One community reported that the number of bike crashes went from 40
in one year to 16 the next. Therefore, they believed their programs were
succeeding. Maybe the programs were; maybe they weren't. But these kinds
of numbers won't prove much, especially if analyzed in a cursory manner.
- A manufacturer of a safety device quoted a police chief as saying
that after ordering lots of the devices for young bicyclists in his town,
there were no more bike crashes that year. True? Probably not. But then,
the purpose was marketing, not science.
These examples show two of the dangers of using bike crash statistics. First,
the numbers are generally very small and, therefore, hard to use with confidence-at
least any justifiable confidence. What, really, does it mean when the police
collect 24 fewer crash reports this year than last year? Probably not much.
Second, reported crashes don't really tell the whole story. Only a small
fraction of a typical community's bike crashes are reported. Some studies
suggest one in five serious car/bike crashes and one in twenty serious non-car-related
bike crashes show up in the statistics. Consider this quote from Jane Stutts
of the Highway Safety Research Center: "In a preliminary study at the
Beaufort County Hospital in Washington, North Carolina, Dr. Frank Sheldon
found that 43 bicycle accident victims received emergency room treatment
during the five-month period from May through September, 1984. At least
half of these involved serious injuries. In contrast, a check of the North
Carolina accident files revealed only 29 police-reported bicycle accidents
in the Washington area over a time span of six years."1
Just what does this mean? To be conservative, assume that 60 bike crash
victims reported to Dr. Sheldon's hospital during each of the six years.
That means over 330 people were seriously injured in crashes that were never
reported. Several authors have described the bike crash picture as an iceberg
phenomenon and it's easy to see why; the visible part is tiny compared to
the rest.
Since the vast majority of crashes are never reported, we really can't say
much about our program's success or failure without going further. One source,
as Dr. Sheldon learned, is the emergency room. While this source may give
a fair indication of the magnitude of the problem, it probably won't help
with crash typing. For that, you're better off with the police reports and,
if you're lucky, diagrams of the crashes.
3. Our helmet program reduced the risk of bicycling head injuries!
Some folks who run helmet campaigns collect data on the number of people
who visit the emergency room due to a bicycle-related head injury. And this
data sometimes shows a substantial reduction in the number of such injuries.
But what do the numbers really mean?
Who knows, especially if project staff don't bother to collect data on the
number of people who rode bikes before they started their campaign and after
they did their work. Clearly, a reduction in bicycling could reduce the
number of bike-related head injuries. And, since no one has told public
health officials to reduce the amount of bicycling being done by citizens
and they haven't claimed to be working under such a mandate, bike use should
be measured as part of any helmet project, particularly one involving mandatory
helmet laws.
Howard Boyd, former National Cycling Officer for Britain's Royal Society
for the Prevention of Accidents, once said "People tend to be most
interested in aspects of road safety that they are not directly involved
inThere is a great deal of interest among legislators in cycling because
it's not something that most of them do."2 This may be one explanation
why there's so much interest in helmet mandation for bicyclists but not
for, say, pedestrians or motorists.
4. The Census shows that many (or few) people bike to work!
Maybe but don't bet your fortune on the Census Bureau's Journey to Work
data. Consider how it is collected. Journey to Work Week happens once every
ten years. It's the last week of March of the Census year. At the start
of April, surveyors call a sample of households and ask how the primary
job holder got to work during the previous week. What kinds of factors could
affect results?
How about weather? A number of studies have suggested that seasons and the
weather play a part in people's likelihood to ride. For example, data from
the recent survey of Missoula's downtown commuters suggested that nearly
twice as many people ride to work in summer than in fall or spring; and
that about half as many ride to work in winter as in spring or fall.3
Consider that in many parts of the country, March is an unpredictable month.
Measuring the number of bike commuters in this manner is nothing short of
a crap shoot. And comparing one community to the next is even worse. If
Town A had a blizzard and Town B had balmy weather, how valid would a comparison
of their bike commuter percentages be? Not very.
Are there other factors that could make the Journey to Work data a bit flakey?
Sure. Focusing on the primary job holder is one. The difficulty of counting
the bike part of a longer multi-modal commute trip is another. Of course,
the point is not to ignore the Journey to Work data but to gather more reliable
data in addition.
5. At this rate, we're never going to get anywhere!
Actually, not true. Since the early days of the bicycle field, we've made
some very significant strides. We've got much better design manuals than
we had in the early '70s. We've gathered lots of experience and have made
significant contributions on a number of fronts-engineering, planning, enforcement,
encouragement, as well as education. But it's important that we keep in
mind the limitations of our knowledge and occasionally critique and re-invent
the field.
Notes
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