Bicycle Saftety Study In Berkeley 2003 to 2010

[Neal]

Hello All,

From Jim Baross post on CABO .....

http://www.sciencedirect.com/science/article/pii/S0001457511001941

Excerpt:

"Police-reported bicycle collision data and
manually collected cyclist count data from bicycle boulevards and
parallel arterial routes in Berkeley, California from 2003 to 2010
are used to test the hypothesis that Berkeley's bicycle boulevards
have lower cyclist collision rates and a lower proportion of
bicycle collisions resulting in severe injury.


While no significant difference is found in the proportion of
collisions that are severe, results show that collision rates on
Berkeley's
bicycle boulevards are two to eight times lower than those on
parallel, adjacent arterial routes.


The difference in collision rate is highly statistically significant,
unlikely to be caused by any bias in the collision and count data, and
cannot be easily
explained away by self-selection or safety in numbers."


Cheers,

Neal

[kulik_000]

This results of this study are not at all shocking. It basically says that bicyclists have fewer collisions with automobiles on
roads which have fewer automobiles and slower moving traffic.

In the summary, it also says that future work ought to involve determining whether the change in treatment of the roadways (the bike
boulevards) makes a positive or negative impact on the rate of collisions between bicycles and automobiles. This was not studied
for this report.

"The streets considered in this study would be appropriate subjects for several related avenues of research. A before-after study of
collision rates on the bicycle boulevards before and after 2003 could help to isolate the effect of the design interventions
undertaken as part of the City of Berkeley's bicycle plan."

The report also indicates researcher bias with the following commentary:

"One is self selection: perhaps arterials simply attract more risk-taking cyclists, while bicycle boulevards attract more
safety-conscious cyclists."

The report also does not indicate whether cycling utility and overall attractiveness was improved by the design treatments of the
bicycle boulevards.

Bruce

[Neal]

Hello kulik_000 and All,

" ...... results show that collision rates on

Berkeley's bicycle boulevards are two to eight times lower than those
on
parallel, adjacent arterial routes."

Maybe not shocking but indicative of how to reduce collisions ......
should you be interested ......

I dunno ..... look what the report states ...... just another flawed
report ........ :)?

Cheers,

Neal

> > parallel, adjacent arterial routes.- Hide quoted text -
>
> - Show quoted text -

[kulik_000]

There are two items that are potentially influenced by this research,
guidance for route selection when making a trip by bicycle, and whether
bicycle boulevard treatment positively or negatively affects collision
rates. Neither of these is advised by this study.

While it seems intuitive that roads with slower and less traffic will have
fewer collisions, we all know that the intuitive thought is not necessarily
the accurate one. In this case the study shows that the intuitive thought
appears to be the accurate one. The question remains whether choosing a
route along a bicycle boulevard (or any parallel side street) is worth the
added time, distance and effort, if any, compared to routing along an
arterial. Clearly, if there is no or little added cost to choosing the
bicycle boulevard over the arterial, than that would be the preferred
choice. On the other hand, if the bicycle boulevard doubled the cost, it
might not be worth the reduced risk. This will, of course, vary amongst
individuals, depending on their comfort level, time permitted for the trip,
and ability to ride in a manner that mitigates the additional risk of
choosing the arterial. It's not clear from the study that riding on any
parallel side street wouldn't also provide the same level of decreased risk
even if not given bicycle boulevard treatment.

That brings us to the second point. Doe the bicycle boulevard treatments
actually increase or decrease safety? The study explicitly disclaims this.
It is added in the "future study" category.

So, we are left with a study that doesn't really tell us anything, but
implies that bicycle boulevards are good to implement. It may be that
bicycle boulevards are perfectly benign, or even beneficial, but this study
does not support either of those conclusions.

Bruce