From: karplus@cse.ucsc.edu (Kevin Karplus)
Newsgroups: rec.bicycles.soc
Subject: Re: Safety and Bikeways
Date: 22 Dec 1992 00:59:44 GMT
Organization: University of California, Santa Cruz (CE/CIS Boards)
Distribution: world
NNTP-Posting-Host: ararat.ucsc.edu

John Forester says

	The design of bikeways is intended to reduce the 1.9% of the
	18% (equals 0.3%) of accidents to cyclists that are caused by
	motorists hitting lawful cyclists from behind while overtaking
	them.

I believe that there are some other accident types that some bikeway
designs address---in particular a bike lane that is made by removing
on-street parking.  Of course, it is the removal of the parked cars,
not the painting of the bike lane stripe that provides the extra
safety.  

Removing the parked cars eliminates nthe collisions with parked cars,
and reduces accidents due to cars or bike pulling out of driveways,
since visibility is substantially impeded by on-street parking.

Thus, to John's 0.3%, I would add 
	Collision with parked car (4%)
	Driveway exit 		  (1%)	about 1/2 the driveway exit accidents
					(excluding wrong-way or sidewalk)

Thus the accident reduction expected is more like 5% than .3%.
Of course, this analysis ignores the main problems with bike lanes:
that they encourage wrong-way riding, left-turns from the right curb,
and motorists turning right in front of bikes.  Adding even small
increases in those types of accidents swamps even my more optimistic
estimate of the possible gains from putting in bike lanes.
And so, I reluctantly agree with John, that bike lanes are probably
not a safety improvement.

(Why reluctantly?  Because bike lanes are the best mechanism I've
found for getting sufficiently wide right hand lanes and parking
elimination---both of which are substantial improvements to the road.
If we could get those improvements without the lane stripes, I'd be
happier, but it is hard to convince traffic engineers, politicians,
and other bicycle advocates of the value of such invisible improvements.)

One problem with John's figures (not his fault) is that Ken Cross's
study is rather old.  The number of adult bicyclists has increased
considerably since 1976 (or whenever Ken Cross's study was done).
Infact, I believe that 1991 was the first year in which adult bicyclist
fatalities exceeded child bicyclist fatalities.  It isn't clear that
the many modern adult bicyclists are as good as the few adults that
were riding in 1976, and so the accident causes may have shifted.
Probably an even larger percentage of adult accidents are
cyclist-caused than in Cross's study.

I agree with John that better education would help enormously, but I
don't see the infrastructure to do it.  There is no mechanism in this
country for educating adult bicyclists (the LAW program is miniscule,
and is mainly preaching to the choir, not reaching those who need it
most).  Even bicycle education for children (who are a captive
audience) is almost non-existant.  The modern material (videos, books,
...) for bicycle education is better than the "bike safety" material
from the 50s, but there are few teachers who know enought to teach the
material, and no interest by the State in funding bike education.


Kevin Karplus
Effective Cycling Instructor
-- 
Kevin Karplus		karplus@ce.ucsc.edu

Due to budgetary constraints the light at the end of the tunnel is
being turned off.
Newsgroups: rec.bicycles.soc