From: JForester@cup.portal.com (John - Forester)
Newsgroups: rec.bicycles.soc
Subject: Safety and Bikeways
Date: Sun, 20 Dec 92 20:30:23 PST
Organization: The Portal System (TM)

                    BIKEWAYS AND CYCLIST SAFETY

   This is in response to questions about why bikeways are
less safe than roads.

Accident Pattern

Accidents to cyclists occur in the following pattern:
Falls                                  44%
Collision with moving motor vehicle    18%
Collision with moving bicycle          17%
Collision with moving dog               8%
Collision with parked car               4%
Bicycle mechanical failure              3%
Collision with pedestrian               1%
Other                                   5%

Collisions with moving motor vehicles in urban areas occur in the
following pattern:

Cyclist on proper side runs stop sign                      9.3%
Motorist turning left hits cyclist headon                  7.6%
Motorist restarting from stop sign hits wrong-way cyclist  6.8%
Cyclist turns left in front of overtaking car              6.1%
Cyclist hit during traffic signal clearance interval       5.9%
Motorist turns right                                       4.8%
Cyclist exits residential driveway                         4.3%
Motorist restarts from stop sign                           4.2%
Cyclist exits commercial driveway                          3.9%
Cyclist on sidewalk turns to exit driveway                 3.0%
Wrong-way cyclist runs stop sign                           2.6%
Wrong-way cyclist hit headon                               2.6%
Motorist exiting commercial driveway hits cyclist
                                             on sidewalk   2.4%
Uncontrolled intersection collision                        2.2%
Motorist exits commercial driveway                         2.1%
Cyclist runs red light                                     2.1%
Cyclist turns left from curb lane, hits car 
                                 from opposite direction   2.1%
Motorist turns right on red, hits wrong-way cyclist        1.9%
Motorist overtaking, does not see lawful cyclist           1.9%
Motorist exiting commercial driveway, 
                                  hits wrong-way cyclist   1.5%
Motorist turning right hits wrong-way cyclist              1.5%

These data are taken from the data sheets of Cross's study of
car-bike collisions and are reported in my book *Bicycle
Transportation*.

AIM OF BIKEWAYS
   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. 

ACTUAL EFFECT OF BIKEWAYS ON CAR-BIKE CONFLICTS
   Practical bikeway designs in urban areas not only do not
reduce any other type of accident to cyclists, but they make the
existing conflicts between cars and bikes more difficult to
manage. Bike paths alongside roadways cause cyclists to ride
closer to driveways, with shorter sight distance and less shy
distance. Bike paths alongside roadways cause cyclists to cross
intersections where they are more likely to be hit by right-
turning cars, by left-turning cars, and by cars from side
streets. In each case, the parties have less convenient viewing
angles, shorter sight distances, and shorter escape distances.
Cyclists who wish to turn left are faced with the humanly
impossible task of looking in all directions at once and yielding
to traffic from all directions at one time. Two-way bike paths
alongside roadways multiply these difficulties by having them
caused by cyclists moving in the wrong direction, which greatly
increases the difficulty of motorists in avoiding them. Bike
lanes in the roadway cause the same difficulties with right-
turning motorists as do bike paths, and the same difficulties for
left-turning cyclists. While cyclists may disobey the bike-lane
stripe to make left turns, the stripe discourages them from doing
so and encourages motorists to believe that cyclists must stay to
the right of the stripe.

EFFECT OF BIKEWAYS ON THE TYPE OF TRAFFIC THAT CYCLISTS ENCOUNTER
   Cyclists on the roadway typically encounter well disciplined
traffic that moves in orderly ways. Cyclists on bike lanes
encounter the same traffic, but when turning right it is confused
by the presence of the bike lane and has a greater tendency to
swerve across the bike lane instead of merging through. Cyclists
on paths find that they ride in a traffic of pedestrians,
children, pets and poorly behaved cyclists that move in chaotic
fashion. 

EFFECT OF BIKEWAYS ON THE RULES OF THE ROAD
   The rules of the road prescribe an orderly set of movements
for drivers of vehicles that can be carried out by normal
persons. The rules of the road for drivers of vehicles fairly
allocate responsibilities and rights in ways that make sense to
drivers and agree with the ways their minds, senses, bodies and
vehicles operate. Adding bikeways and bikeway rules to the rules
of the road for drivers of vehicles complicates the system so
that nobody knows who has which responsibilities or which rights.
For example, with a cyclist on a bikeway to the right of a right-
turning motorist, who has the right of way? These are not
situations that can be decided by a legislature, as if just
making a law would solve the problem, because the situation
itself defies solution by normal standards. Human beings cannot
operate safely in these situations because the situations demand
more of them than they can do. In any case, the typical situation
is to require the cyclists to yield the right of way and delay,
merely because the bikeway has created a more dangerous situation
than existed before. This is particularly obvious in the case of
the traffic signals with special cyclist phases that are used in
Europe. These signals delay cyclists to keep them from moving in
conflict with cars, when if the cyclists were not on bikeways
they could move without coming into conflict with cars. 

EFFECT OF BIKEWAYS ON THE NUMBER OF CONFLICT SITUATIONS
   To make a trip from arbitrary origin to arbitrary destination
in the typical urban area requires that cyclists cross a certain
amount of traffic, the traffic that crosses their path. Practical
urban bikeways do not reduce the amount of crossing traffic. They
also make it more difficult to handle. They either cross the
traffic midblock, where it is more dangerous than at intersec-
tions, or they cross at or adjacent to intersections, where they
make it more dangerous still. If the bikeways run on low-traffic
streets, as is frequently recommended, they have fewer traffic
signals to protect the cyclists from intersection conflicts than
if they ran on high-traffic streets. If bikeways run on low-
traffic streets they may reduce the amount of turning conflicts
simply because there is less traffic to turn, although this has
not been demonstrated, but they lack the turning lanes that make
turning traffic much safer by changing swerves across to merging
throughs. 

SUMMARY
   Practical urban bikeways, even if they worked perfectly, could
not do much to reduce accidents to cyclists because they are
aimed at only 0.3% of accidents to cyclists. In fact, they
somewhat increase the number of conflicts that cause car-bike
collisions and greatly increase the difficulty of handling them,
while also, for paths, greatly increasing the number of bike-ped 
conflicts. 

JForester@cup.portal.com                John Forester
                                        726 Madrone Ave
408-734-9426                            Sunnyvale CA 94086 USA