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THE EFFECT OF BIKELANE SYSTEM DESIGN
UPON CYCLISTS' TRAFFIC ERRORS
August 1978; Revised April 1982
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INTRODUCTION
Various attempts have been reported to describe cyclists' behavior, sometimes in
quantitative terms, for purposes of driver qualification, highway design,
traffic law enforcement, and athletic coaching. Aside from athletic coaching and
the informal evaluation of one cyclist by one or more others during many club
rides, which are usually done accurately and comprehensively, all reported
systems of cyclist evaluation are seriously deficient. This paper first
describes, in the context of present practice, a cyclist behavior recording
system suitable for evaluating either individual cyclists for proficiency or a
population of cyclists for cycling behavior. It then discusses the results of
evaluating the behavior of 4 different cyclist populations in cities with 3
different types of bikeway system, showing that cyclist behavior varies
according to the type of bikeway system. Specifically, when comparing the
behaviors of populations of cyclists from different cities whose bikeway systems
have different design characteristics, each population shows a higher proportion
of those traffic errors which the particular system design would be presumed to
encourage, even though those errors are known to be significant causes of
car-bike collisions.
EARLY CYCLIST-BEHAVIOR EVALUATION SYSTEMS
The type of evaluation most commonly used in the U.S. is the stationary,
single observer, who observes the behavior of cyclists passing a point,
generally according to a very restricted set of variables, part of which may be
a classification system based on a few immediately-understandable visual cycling
characteristics, such as general type of bicycle and age or sex of cyclist. This
system is both defective and limited. It is defective in that the critical
portions of many cyclist maneuvers, and many maneuvers themselves, do not occur
in front of the observer. For example, an observer stationed to observe an
intersection often cannot see whether a cyclist properly performed the
intersection approach maneuvers, and these are critical to the safety and
acceptability of the cyclist's actions. Also, only the most obvious cyclist
characteristics can be observed as the cyclist goes by. The system is limited in
many ways. Many maneuvers do not occur at predictable locations, so their
observation cannot be planned. It is commonly believed that different types of
cyclist exhibit distinctly different patterns of behavior, but this system does
not permit the multiple observations of a single cyclist required to validate
this hypothesis. The system cannot evaluate the performance of a single cyclist
to serve as a competence test. Even though the observations may be made at many
locations according to an elaborate plan, there is no assurance that the
maneuvers or situations observed constitute an unbiased estimate of the actual
proportions of all types of maneuver that are performed by the population of
interest. These defects are equally detrimental whether the observer records
contemporaneously or at some later time through a visual recording system, be it
electronic [what is now called video], photographic, or any other.
Cycling proficiency tests are given to a large proportion of the adolescent
population of cycling-oriented European nations using the multiple, stationary
observer technique. A fixed course is laid out, observers are stationed at
presumably critical points, the cyclists are each identified by a conspicuous
number, and are dispatched at intervals to ride the course. The observers
evaluate each cyclist in turn, recording the evaluation by cyclist number.
Common though this system is, it is not ideal even for evaluating individual
cyclists because the specific traffic situation necessary for evaluation may not
occur during the single pass through the observing location, and in any case it
cannot serve the scientific purpose of evaluating populations of cyclists in
their actual maneuver proportions.
Several American investigators have trailed cyclists with a car, recording
the results. This is unsatisfactory because the slowly-moving car blocks the
overtaking motor traffic with which the cyclist should be interacting, thus
destroying the normal traffic pattern.
IMPROVED CYCLIST-BEHAVIOR EVALUATION SYSTEM
The observer who follows by bicycle, however, does not disturb the traffic
pattern. Neither does he disturb the typical American cyclist who has not been
informed that he is being observed, because the typical American cyclist doesn't
look behind in his typical urban trip. (That's one reason for the excessive
car-bike collision rate.) In a proficiency testing situation, the observer can
direct the course of a small group of cyclists (up to about 8) until he has
obtained all the observations that he requires for complete evaluation. In a
population evaluation situation, if the observer selects a cyclist, follows him
to either his destination or the boundary of the observation area, and then
returns toward the center of the area until he sees another cyclist to follow,
he will select cyclists in a substantially random pattern and will observe the
actual mix of cyclists. The problem is how to record the observations while
A cyclist cannot write while cycling, and probably cannot accurately push
buttons in a digital coder. But he can talk, and a portable tape recorder can
record the observations for later tallying. The portable recorder is best
carried in a small backpack, with its microphone clipped to the shoulder strap
near the cyclist's mouth. (This type of microphone is called a &lapel
mike& and is easily available.) The remote control circuit is wired to a
pushbutton which is mounted on a thumb stall that is secured to the cyclist's
thumb by a bandage-like strip of cloth with hook and pile fasteners. (Pushbutton
Electrocraft 35-418, for printed circuit boards, is a comfortable shape. Mount
it on the thumb stall with silicone sealing compound.) The observing cyclist then
pushes the button whenever he wishes to record, so the tape runs only when he is
actually recording. This conserves batteries, tape and subsequent tallying time.
I have found that a 30-minute recording (one side of a C-60 cassette) is
sufficient for an 8-hour observation period in a college city.
In order to both have a common scoring method and to be able to tally from
recorded oral observations it is necessary to have predetermined names for most
traffic maneuvers and their errors. The cyclist proficiency score sheet (Figs 1
and 2) lists almost every cyclist traffic maneuver and its typical errors. With
these names in mind, the observer merely records the maneuver name, and
evaluates it as either &OK& or lists the errors made. Any
characteristics not on the score sheet may also be recorded, and the evaluation
later adjusted accordingly. Score values are shown on the sheet, but it is not
the purpose of this paper to discuss scoring. It considers only the observed
proportions of defective maneuvers and the typical errors. The standard of
behavior used as the criterion is that described in Effective Cycling.
(1, §3) Those maneuvers listed on the score sheet that affect other traffic are
easily distinguished and observed. Only a few of the deficiencies observed
present significant problems of detection or evaluation. All of the maneuvers
that showed statistically significant frequency differences in this study
present no significant problems of detection or evaluation. The observed cyclist
action clearly either does or not exhibit the deficiency in question. This
scoring system ignores cyclists who ride on sidepaths or on the wrong side of
the road. Their actions are so universally wrong that they cannot be rated
against the standard.
OBSERVATIONS USING THE IMPROVED SYSTEM
Using this technique the cycling populations of three California university
cities with different bikeway characteristics were evaluated, and were compared
with a population of typical club cyclists. All observations discussed herein
were made by the author on normal business and academic weekdays in fair
weather. The cities are: Berkeley, Davis and Palo Alto. All three cities have
universities of high repute, with approximately equally-intelligent students.
Their street and traffic situations are different, resulting in different
bikeway system designs. Berkeley has relatively narrow streets with moderate to
heavy traffic volumes. In some areas it is so hilly that downhill bicycle speeds
exceed those of the cars, but few cyclists are seen there. It has no significant
bikeway system. Davis has wide streets with low traffic volumes, practically no
externally-generated traffic, and an unhurried motorist attitude. Davis has
bikelanes on its wide arterials, but not on its normal residential streets.
Davis also has its bikelanes positioned between right-turn-only lanes and the
curb, at those locations where there are right-turn-only lanes. Palo Alto has a
combination of easy, low-volume traffic on its residential streets and moderate
to heavy traffic from other areas on its arterial streets, which are nearly all
too narrow for bikelanes. It has placed its bikelanes upon its residential
streets, where they are obstructed by stop signs at 50% of the intersections.
The club cyclists all lived and frequently cycled in the Palo Alto area, and
their behavior was evaluated in a ride traversing the cities of Menlo Park, Palo
Alto, Mountain View and Los Altos. However, their cycling behavior does not
change from place to place, because they ride proficiently wherever they may be,
and regardless of the type of bikeway system provided. California, it should be
noted, does not have a mandatory bikepath law.
SAMPLE SELECTION
None of these groups is a control group, for it is extremely difficult to
obtain and to use control groups in this type of investigation. The difficulties
are many. Experiments involving control groups require samples either matched
for all relevant characteristics or samples selected without bias from the same
population. The experimental factor must be applied to only the specified groups
in a logical manner. All groups must then be subjected to the same procedure and
test. In this investigation one postulated effect of bikeways is to develop a
new, larger and less competent cycling population. (At least, that is the effect
that is claimed and desired by bikeway advocates, and the lower proficiency was
observed herein.) While important knowledge may be gained by observing, as
reported herein, that the behavior of a population of competent club cyclists is
unaffected by the presence or absence of bikelanes, it is also mandatory to
observe the behavior of the population that actually uses the bikelane system.
Matching the cycling populations for experience or for other factors would
invalidate the investigations of the cycling behaviors of the populations that
are actually attracted by the particular facility types. Even if matching were
desirable, the appropriate match would probably be between those portions of the
total populations in the areas of interest which are reasonably equally
susceptible to using cycling transportation, a condition which is substantially
impossible to achieve, even in these areas which are probably much more similar
than areas randomly selected from the entire U.S. Furthermore, the experimental
factors cannot be applied to each group in a systematic way, because the factors
are not under the experimenter's control. He must accept them as they are
applied by entirely unassociated entities. The experimental populations could be
placed under the experimenter's control, so he could move them to locations
where the different experimental factors exist, but that would invalidate the
experiment by destroying normal transportation habits, as discussed below.
Lastly, the test conditions are different for each group. The scoring system is
the same, but the operating conditions are not. They are unique to each area.
Suppose a standardized test were developed, for example by requiring each
cycling population to travel to another city in which none of the test
populations normally rode. While something might be learned through such a test,
it would not and could not be a measurement of the behavior in the actual
conditions. Transportation is largely an habitual activity. Were an experimenter
to move groups of subjects around to different areas in accordance with an
experimental plan, the subjects would behave differently than they do in their
normal transportational activity. In short, despite the scientific ambiguities
produced, the investigator must accept the composition, location, and
environment of the subject groups as they exist.
The groups were selected not in accordance with an experimental plan, but as
exemplifications of different situations which have been deemed significant in
the bikeway controversy, with as much similarity in other conditions as could be
reasonably attained. Davis is universally accepted as the bikeway capital of the
United States, and, like many such places, serves a university clientele. Palo
Alto is widely considered to exemplify bikeway systems for employed adults, with
some university participation. Furthermore, these two exemplify two different
bikelane system design concepts: arterial street bikelanes contrasted with
residential street bikelanes, but each is in a suburban setting in which
bikeways were easy to install. Berkeley exemplifies the metropolitan university
situation in which traffic is heavy but bikeways are difficult to install and
are practically insignificant. All these areas have high cycling volumes by U.S.
norms. The population of club cyclists was selected as exemplifying the
normative standard of safe, legal and proper cycling, and the safety standard of
being the group with the lowest known accident rate. That these groups are all
in Northern California is not entirely due to the fact that the investigator
lives there. Had Gainesville, Florida, been selected to exemplify university
sidewalk cycling, the enormous difference in cyclists' social status and
training between Northern California and Florida would have been injected into
the investigation. In my opinion, California, particularly the north central
portion, presents the best investigative location in American cycling, because
the combination of intense cycling activity (by U.S. norms) and widespread
governmental involvement has exposed a relatively homogenous (again, by U.S.
norms) cycling population to practically every type of facility, stimulating
both cycling and engineering competence to an unusual degree.
The city cyclists were selected by a random process that selected cyclists
with a probability proportional to the time that they spent cycling in their
area on the days of observation, which were normal business and academic
weekdays in fair weather selected by the happenstance of the observer's
convenience. In all substantial respects this is a random sampling of the
cycling activity within each area.
The club cyclists were arbitrarily selected by the process of observing all
those that showed up at the start of a regularly scheduled weekday urban touring
ride with a scheduled duration of 2.5 hours. There is no reason to suppose that
they are not representative of club cyclists in general, and observation shows
no characteristic in which they are unusual. They were told that the observer,
who is a frequent cycling companion of theirs, would observe their riding events
and record his observations on voice tape. The leaders were asked to take a
route to their destination that had more traffic and more difficult spots than
the normal route, and the observer rode at the rear and for less than 4 minutes
in a 2-hour ride spoke into his lapel microphone in a tone that very few of the
riders ever heard. The club cyclists rode much of their route in far more
difficult traffic conditions than were observed for any of the city cyclist
populations.
CRITICAL CONCERNS IN SAMPLE SELECTION
These differences in test conditions may suggest to some that the club
cyclists' performance is therefore not comparable to the performances of the
others, an objection that is obviously appealing to those who think that their
performance is too good. This objection is pertinent only on the interpretation
that the club cyclist performance represents an estimate of the average
performance of a trained population. If it is taken simply as a demonstration
that the normative standard assumed by the rating system can be met and
maintained under difficult conditions for substantial periods of time, it
doesn't matter whether the club cyclists knew they were being observed or not.
Observation cannot make the impossible possible.
If, however, the club cyclist performance is taken as an estimate of the
performance that would be achieved by a trained population in normal cycling
transportation, then the significance of the bias introduced by the three known
differences must be estimated. Since the only behavioral differences between
populations that were detected and are discussed in this paper are those
associated with left turns and lane changes by cyclists, positioning of cyclists
with respect to right-turning cars, and the behavior of cyclists at stop signs,
the estimation of bias need cover only these maneuvers. In this case, bias can
only exist in one way: the club cyclist performance could not get significantly
better. Thus the assumption of bias requires the additional assumption that in
the absence of observation the club cyclists usually turn left or change lanes
leftwards from the curb lane without looking, position themselves on the
right-hand side of right-turning cars, and run stop signs without slowing or
looking. This assumption is highly improbable. Since the club cyclists were
riding and talking about other matters, they were riding by habit, without
conscious notice of the observer. Not only was this obvious to the observer, but
the cyclists volunteered this information during discussion at the end of the
ride. If their habitual cycling styles were different from that observed, these
habits would have betrayed them at least some of the time, something that did
not occur. I, the observer, had spent at least several hundred hours riding with
club cyclists, singly and in groups, in urban traffic, before consciously
deciding to record their behavior, and I noticed no significant difference
between observed and unobserved behavior. Since the greater part of the
behavioral differences are merely the action of looking for the traffic pattern
and conforming to it, so the cyclist can preserve his life at no cost to
himself, it is irrational to expect that cyclists who have learned how to do
this would largely forgo the opportunity to do so merely because they are
unobserved.
The assumption of less competent, more dangerous behavior when unobserved is
also denied when considering the source of the putative more competent behavior.
The cyclists observed had no advance knowledge that they would be observed, and
therefore had no opportunity to specially learn good technique. Nearly all had
had no formal cycling training of any type. (One had participated in an
Effective C he did not lead the group, nor did he behave
differently from the others.) There is no possibility that they could have
learned the skills that they displayed from any of the bicycle safety campaigns
to which they undoubtedly had been exposed, because no such campaigns consider
the necessary skills that are displayed and are discussed herein. The only
possible source for their skills is the practice of club cycling. Therefore,
they must have been exhibiting normal club cycling behavior, which contradicts
the premise that they were exhibiting better-than-club-cycling behavior.
The car-bike collision statistics also contradict the assumption that the
club cyclists behaved unusually well because they knew that they were being
observed. Cross's car-bike collision statistics, as analyzed by Forester (2, 56
ff) show that cyclists learn how to avoid car-bike collisions that are caused by
not looking and not conforming to traffic, because these constitute a decreasing
proportion of car-bike collisions as the ages of the cyclists increase. Without
observation, cyclists imp there is therefore reason to
believe that these experienced cyclists would be better than average, which is
what the data show.
CALCULATIONS
The number of cyclists in each location and the extent of the evaluation, as
shown by the number of earned points, are given in Table&nbsp1. The points
lost and average score are given for rough comparison. Note that the number of
earned points per cyclist varies. Only 8 club cyclists were evaluated, but their
total earned points exceed those of the 71 Davis cyclists. The earned points per
cyclists varies with the length and complexity of the trip, which in the random
sampling situation is entirely controlled by the observed cyclist.
For each cyclist each traffic maneuver and its errors, if applicable, were
tallied on a proficiency score sheet. These tallies were then summarized onto a
sheet for each group which listed, for each traffic maneuver, the number of
performances and the number of times it was done incorrectly. Seven types of
maneuver showed a sufficient number of instances with sufficiently different
proportions defective to indicate statistically valid differences in behavior
between populations. The statistic used to determine significance is the formula
for the normal distribution of differences in proportions:
z= { p1 - p2 } / SQRT { p(1-p)( { 1/ n1 } + 1/ n2) }
STATISTICALLY SIGNIFICANT DIFFERENCES IN BEHAVIOR
The data for those maneuvers that have statistically different proportions
defective between the various locations are shown in Table 2. The types of
errors in these maneuvers are shown in Table 3. The differences that are
statistically significant in proportion defective between locations are shown in
Table 4, listed as showing either 95% or 99% probability that the populations
indeed behaved differently.
The maneuvers may be grouped as:
1 Yielding to traffic at an intersection that is controlled by a stop sign or
a traffic signal.
2 Cyclist making a left turn, including the lane change and the turn.
3 When motorist may turn right, including the cyclist avoiding the
right-turn-only lane, approaching the intersection, and getting on the
right-hand side of a moving car.
These are very important maneuvers. According to Cross's urban data (1, urban
data only), cyclists running stop signs or signals cause 14% of urban car-bike
cyclists turning left cause 9%; motorists turning right cause 7%.
For traffic signals, Berkeley cyclists are statistically the worst, but this
is because of one traffic signal at a main campus entrance at which cyclists
proceed on a 4-way WALK signal. Considering the American situation, they should
not have been considered deficient, because 4-way walks are often intended for
cyclists even though this is against the law.
At stop signs, Palo Alto cyclists are significantly much worse than all the
others, and the typical error is proceeding without slowing or looking. As the
observer behind, usually less than 50 feet behind, I have seen them go through
one stop sign after another without the slightest variation in pedal speed and
without the slightest head motion to indicate sideways watchfulness. See Table
For cyclists making left turns and lane changes, both Palo Alto and Davis
cyclists are much worse than club cyclists, with Berkeley cyclists approximately
in the middle. The typical error in turning left is turning from the curb lane
without looking behind, and in lane changing is doing so without looking behind.
See Table 3.
The situations in which the motorist may or does turn right run from the very
general one of selecting the incorrect approach path for a major intersection,
through the specific error of riding straight through in or on the right of a
right-turn-only lane, to the specifically dangerous error of riding through an
intersection on the right-hand side of a car that may turn right. In the general
positioning situation, all non-club cyclists are significantly worse than the
club cyclists. In my experience, the general precautionary technique of always
approaching every major intersection just to the right of the straight-through
cars, and no further right, lest some motorist arrive in the wrong position, is
one of the last standard habits the American cyclist learns. Advancing to a
specifically incorrect procedure, riding on the right of right-turn-only lanes,
Davis cyclists have as high a deficiency rate as in general positioning, but
Berkeley cyclists become as good as club cyclists. Palo Alto doesn't score on
this because Palo Alto cyclists traverse very few intersections with
right-turn-only lanes. This relationship is retained for the specifically
dangerous maneuver of traversing a major intersection on the right of a car that
may turn right. The rate for Davis is twice that of Palo Alto, and is more than
10 times that for Berkeley. Club cyclists show no errors of this type - they've
learned what not to do.
The deficiencies listed on the score sheet for these maneuvers, which are
those that have statistically different deficiency rates between the
populations, are clearly highly related to safety. Actions like changing lanes
without looking, or running a stop sign too fast to yield to traffic, cannot be
considered safe behavior, and have been demonstrated to be significant causes of
car-bike collisions. Even more significant are the typical patterns of
deficiencies, in which two complementary deficiencies, such as excessive speed
and not looking, are combined into one instance.
OBSERVED RELATIONSHIP BETWEEN CYCLIST BEHAVIOR AND BIKELANE SYSTEM DESIGN
Previous analysis of the traffic patterns associated with bikeways (2, chap
8) shows that urban transportational bikeways of any type contradict the normal
rules of the road in three situations: cyclist overtaking motorist, cyclist
turning left, and motorist turning right. This analysis clearly shows that the
bikelane maneuvers for these situations are far more dangerous than the
corresponding normal maneuvers. This is supported by the car-bike collisions
statistics that are quoted above. The cyclist overtaking motorist situation
causes a car-bike collision if the motorist turns right, as when the cyclist
approaches the right-hand side of a motorist who is turning right, so that these
observations cover the three situations in which previous analysis had shown
that the bikelane principle contradicted the normal rules of the road.
Bikeway advocates argue that this analysis is incorrect because the traffic
laws require otherwise. Indeed they do, but this study is concerned with how
people believe bikelane traffic should operate, as exemplified by how they
behave around bikelanes, rather than with legal niceties that road users do not
understand. In California at the time these observations were made the state
statutes had long superseded the local statutes and specifically required (as
they still do) both cyclists and motorists in these three situations to disobey
the bikelane principle and to obey the normal rules of the road instead. This
legal requirement is not merely implied by the absence of contrary instruction,
but since the bikelane statute specifically allows the normal maneuvers, and
none others, the requirement to follow the normal rules of the road is legally
clear. Not only was the law clear, but the bikelanes had been in place for a
sufficiently long time for initial disturbances to settle out. The Davis system
had been in effect for 10 years, the Palo Alto system for 5 years. Therefore,
the effects that were observed must be considered the long-term effects of any
bikelane program on the understanding and behavior of both motorists and
The depths of misunderstanding are shown by three associated investigations.
I observed Davis motorists turning right at a bikelaned intersection directly
across the street from police headquarters. 20 out of 20 right-turning motorists
made wide right turns across the bikelane instead of first merging to the curb
as the law required. In Mountain View, the installation of bikelanes on
Middlefield Road (which I used frequently) was observed to raise the proportion
of motorist wide right turns from 10% to 70%. In Davis, I drove a car repeatedly
through right turns at an intersection at which all motorists had to turn either
left or right, while most cyclists proceeded straight across into the campus
area. On each circuit I approached the intersection slowly, with my right-turn
flashers operating and my right-hand wheels in the bikelane. Despite these
obvious clues to my intention, 10 Davis cyclists out of 11 overtook in the
narrow space between my car and the curb.
These investigations show that bikelane systems are associated with larger
proportions of dangerously defective cyclist and motorist behavior than occur in
similar cycling populations who ride where there are no bikelane systems, and
that the typical dangerous errors are those that are most likely to be
encouraged by the design of the bikelane system.
Because of the emotional nature of the bikeway controversy, many objections
will be raised to this conclusion. There is certainly some validity in arguing
that while the Berkeley, Davis and Palo Alto student populations are comparable,
neither those who cycle in each city nor the cities themselves are comparable.
Furthermore, there is always the question of the causal relationship - do
bikeways cause dangerous cycling or does dangerous cycling cause bikeways? Or is
there some other relationship - contemporaneity without causality, or a more
complex causal relationship?
To summarize the traffic patterns, Davis has easy traffic on very wide
streets, Palo Alto has easy traffic on residential streets but moderate traffic
on arterial streets that are too narrow for bikelanes but ample for cycling,
while Berkeley has moderate to heavy traffic on all streets, nearly all of which
are too narrow for bikelanes but ample for cycling. Davis and Palo Alto are
flat, Berkeley is moderately hilly where most cyclists ride and very hilly
elsewhere. Certainly the cities are different, and these differences constrained
both the cyclists and the bikelane systems. Davis streets are so wide that it
got its bikelane system without losing any parking. To have extended it beyond
the arterials would have removed parking from one side of the residential
streets, and the residents evidently didn't think that that was desirable. After
all, their original interest in bikelanes was to prevent student cyclists from
blocking the arterials, and their original move, which proved unlawful, was to
prohibit cycling on the arterials. Palo Alto got its system at the price of
removing parking from one side of a few of the bikelane streets, in a city in
which overnight parking is prohibited and in which parking and motor traffic are
discouraged. Berkeley could get bikelanes only by taking parking in a city in
which there are insufficient off-street parking places for its residents' cars,
and in which the cars of students fill all parking spaces for much of the
downtown area every working day. Palo Alto attempted to overcome its political
problems by decreeing that its arterial sidewalks were mandatory bikeways, but a
54% increase in car-bike collisions per bike-mile scotched that plan. If you
believe that urban transportational bikeways are needed (which I consider a
false postulate) these three cities well illustrate the paradox that bikeways
are only provided where unnecessary and can never be provided where the need is
greatest. The situation is certainly not ideal for scientific elucidation, but
it does represent the mix of situations that are likely to occur in the real
Another objection is that behaviors on bikelane and non-bikelane streets
should have been compared within each city, thus eliminating the effects of
skill differences produced by, for example, the refusal of many persons to cycle
where heavy traffic exists without bikeways. This approach had been considered
but was rejected because differences between cities were clearly obvious before
organized data collection was started, while differences between streets were
not. Quite obviously, the major difference to be explained is between cities,
not between the streets of one city, and the categories which are differentiated
determine the type of explanation that will be deduced. This investigation does
not demonstrate that the presence or absence of a bikelane on any particular
street has any effect on cyclist behavior, and I believe that such effects are
generally insignificant, with certain specific exceptions at particular
locations. This investigation does show that the predominant effect is that the
type of bikelane system to which cyclists are predominantly exposed (since few
American bicycle riders travel sufficiently far to be exposed to more than one
system at any one period of their lives) determines their cycling habits, which
are then used on both bikelane and non-bikelane streets, and presumably are
transferred to other types of bikeway also.
However, other differences may be significant - particularly the differences
in traffic intensity (volume and speed, relative to capacity). Berkeley has more
intense traffic than either Palo Alto or Davis, but better cycling behavior from
a small cycling proportion of the population. It is at this point that the
ambiguities concerning causation enter.
POSSIBLE CAUSAL RELATIONSHIPS BETWEEN CYCLIST BEHAVIOR AND BIKELANE SYSTEM
I asked above whether bikelanes cause dangerous behavior or vice versa. I
consider that, although the effects travel in both directions, considering
behavior as the cause is often more fruitful than considering behavior as the
result. This is not an absurd question, because undoubtedly dangerous cycling
behavior is one cause of bikeways. The prime advocates for bikeways expect most
cyclists to ride improperly. Whether this is because they don't themselves know
how to ride properly or because they hope to attract a cycling population from
those who don't, or because they simply want to get incompetent 'nuisance'
cyclists off the roads, is immaterial. Contrariwise, persons who advocate
competent cyclist behavior are not numbered among bikeway advocates. Bikeways
are caused
they are clearly not provided by highway
departments on the excuse that they would prefer providing better roads but
haven't the money to do so. Since there is clearly a causal relationship between
one's perception of the prevalence, acceptability, and even the desirability, of
incompetent cycling behavior and whether one becomes a bikeway advocate,
deficient cyclist behavior is a cause of bikeways.
Bikeway systems are frequently claimed to have three beneficial effects. They
are said to make cycling safe by substantially reducing car-bike collisions.
They are said to teach inexperienced cyclists how to ride properly. They are
said to attract many persons to cycling.
What evidence does this study show for the hypothesis that bikelanes
substantially reduce car-bike collisions? Bikelanes could accomplish this result
by reducing two kinds of behavior: dangerous motorist actions and dangerous
cyclist actions. Quite clearly, the data show no lower proportions of dangerous
cyclist behavio rather the data show high proportions of 6
types of dangerous cyclists' behavior in bikelane cities.
The data show no lower proportions of dangerous motorist behavior in bikelane
if anything, the data show the reverse, with larger proportions of
right-turning motorists turning from the left-hand side of straight-through
cyclists. No car-bike collisions were observed during the study, which is the
statistical expectation. The observational technique did not specifically
observe dangerous motorist behavior, but it recorded the cyclist's reaction to
such behavior whenever that occurred. Only one type of dangerous motorist
behavior was observed to be statistically significant: motorists turning right
from the left-hand side of straight-through cyclists were frequent in the
bikelane cities but were absent in the non-bikelane city of Berkeley, and for
club cyclists. Three evasive maneuvers to avoid motorist errors were observed: 2
Avoid Motorist Right Turns and 1 Avoid Motorist Exiting Stop Sign, all in Palo
Alto. Despite the prevalence of motorist right turn situations in Davis, no
cyclist was observed to take the appropriate evasive action of turning right
inside the motorist' the very low traffic speed made this unnecessary.
The data show that motorist actions that are dangerous to cyclist are quite rare
except for motorist right turns in bikelane cities.
The argument has been made by bikeway advocates that the Davis bikelane
system must be satisfactory because of the long absence of fatal car-bike
collisions. This absence is probably due more to the Davis conditions than to
the bikelane system. Fatal injuries are rare in car-bike collisions, occurring
in less than 1% of car-bike collisions, and are generally associated with high
impact speeds. Davis motor traffic is low volume and low speed, and Davis
motorists are both very easy-going and very considerate of dangerous cyclist
behavior, all factors that reduce car-bike collisions, particularly fatal ones.
These factors would exist and would protect cyclists whether or not Davis had
bikelanes. The important point to make is that if Davis cyclists were to ride in
other cities with their same lack of competence, their car-bike collision rate
would be very high. The fact that it is the conditions and not the bikelanes
that permit this dangerous cycling is demonstrated by the fact that the
dangerous cyclist errors observed in bikelane cities were those against which
bikelanes offer no protection at all. The argument that Davis cyclists are only
as competent as the conditions demand (which has been made by bikeway advocates)
merely emphasizes that bikelanes in Davis are more useless than anywhere else,
because the considerate motorist behavior compensates for extreme cyclist
carelessness.
Equally trenchant is the refutation of the argument that the Davis bikelanes
protect cyclists against dangerous motorist errors. The only motorist error
against which bikelanes are intended to protect is the motorist overtaking
cyclist car-bike collision that is caused by the motorist who either doesn't see
the cyclist or doesn't know the width of his own vehicle. The Cross data show
that this type of car-bike collision is rare in cities (2% of urban daylight
car-bike collisions) and the most prevalent conditions are narrow 2-lane
rural-type roads without street lighting during darkness. With its wide,
well-illuminated streets and slow traffic, and with its motorists who very
obviously (as demonstrated herein) take extreme care for cyclist safety, Davis
presents the least motorist danger to cyclists of almost any city in America.
Those who argue that the Davis bikelane system is necessary to protect cyclists
from motorist errors do not argue from facts.
Furthermore, it is improper to consider the absence of reported fatal
car-bike collisions as indicative of ge the UC Davis
hospital emergency room averages several severe cyclist injuries per week.
Cycling is not safe in D this observer found it necessary to ride with
extreme caution to avoid the incompetent cyclists, just as Davis motorists have
The data of this study therefore oppose the hypothesis that bikelane systems
significantly reduce car-bike collisions and support the contrary hypothesis
that bikelane systems at least increase the probability of car-bike collisions
by increasing the proportion of actions that cause car-bike collisions.
What evidence does this study show for the hypothesis that bikelanes teach
inexperienced cyclists how to ride properly? Since the bikelane cities had the
significantly higher proportions of dangerously defective cyclist behavior, and
since at least the Berkeley and Davis cycling populations had very similar
origins, it appears that bikelanes do not teach their users proper cycling
technique as rapidly as does cycling on the normal roadway. The greater cyclist
volume in Davis does not justify the contrary argument, because greater cyclist
volume would be expected to make cyclist learning proceed more rapidly, not less
rapidly, both because of the greater prevalence of correct cyclist models to
learn from and because of the more frequently observed consequences of incorrect
behavior. One might argue that the Davis bikelanes have a more difficult
teaching task because Davis conditions (not necessarily only the presence of
bikelanes) attract less competent persons to cycling. If so, then the most
favorable evaluation possible is that bikelanes possess insufficient
instructional power to train the large number of cyclists that bikeway advocates
hope to develop. One must conclude that bikelane systems show no signs of
teaching proper cycling technique, but rather of hindering the learning of
proper cycling technique.
This study contains no evidence concerning whether bikelane systems are
significant creators of new cyclists. The well-accepted differences in
proportions of cyclists in the total populations of the three cities are
probably due to causes other than the bikelanes. However, bikeway advocates
argue that the Davis bikeway system created the Davis cycling population. Well,
if their argument is considered to be correct, then it is reasonable to conclude
that the dangerous cyclist behavior that was observed in bikelane cities has
been caused, at least in part, by those persons who, but for the bikelane
system, would not have been cycling.
Bikelanes have been criticized for creating car-bike collision situations,
for making it harder to learn proper cycling technique, and for enticing new
cyclists into a dangerous activity with false promises of safety. These are of
course the opposite of the claims of bikeway advocates that have been discussed
above. As was concluded above, the data support each of these anti-bikelane
hypotheses better than they support the pro-bikelane hypotheses.
However, there remains the question of whether these observed differences
could have been caused by some other agency. The most serious criticism is that
the differences between the cycling conditions of the cities caused different
cycling populations to be selected from the geographical populations. The most
pertinent criticism is that Berkeley conditions select the few competent
cyclists from the population, whereas Davis conditions attract most of the
population, thus creating a cycling population that naturally exhibits a higher
proportion of dangerous deficiencies. One's approach to this question depends
greatly upon one's view of the origin of cycling competence.
Bikeway advocates appear to assume that the ability to cycle competently is a
rare and innate attribute, because they argue that bikeways are intended for the
great majority of cyclists, not for those whom they claim are the elite few
competent cyclists who oppose bikeways. If indeed the potential ability to cycle
competently in traffic is rare, and since, as this study shows, bikelanes do not
correct for the absence of that ability, then bikelanes are an entirely
inappropriate social response to transportation problems. It is unethical to use
false promises of safety to entice persons into an activity which, by the
bikeway advocates' own theory, they cannot perform safely.
Bikeway opponents adopt the opposite view of traffic-cycling ability. They
claim that the potential ability to cycle competently in traffic exists in
almost all people, but must be developed by training. Quite obviously, if one
believes in this view one must support training under normal road conditions,
both because normal road conditions are the actual operating conditions and
because learning is easier and quicker under normal road conditions than under
bikeway conditions. Equally, one must oppose bikelanes for the corresponding
reasons: they cause average cyclists to operate dangerously, they cause average
motorists to operate dangerously, and by complicating both cyclist and motorist
training they so effectively delay learning proper operating technique that only
expert cyclists learn to operate safely.
In other words, whether one adopts the bikeway advocates' view that
traffic-cycling ability is inherited, or the effective cycling view that
traffic-cycling ability is a generally-possessed, trainable function, one is
compelled to conclude that bikelanes are an inappropriate social response to
current transportational problems.
REFERENCES
1 Forester, John: Effective Cycling: 1975: Now fifth ed, 1984, The
M.I.T. Press, Cambridge MA 02142
2 Cross, Kenneth D., & Gary Fisher: A Study Of Bicycle/Motor-Vehicle
Accidents: Identification of Problem Types and Countermeasure Approaches:
1978: National Highway Transportation Safety Administration: avail able from the
National Technical Information Service, Springfield VA 22151
3 Forester, John: Cycling Transportation Engineering: 1977: Now
superseded by Bicycle Transportation: 1983: The M.I.T. Press, Cambridge
4 Kaplan, Jerrold A.: Characteristics of the Regular Adult Bicycle User:
1975: Univ. of Maryland Master's T available from the National Technical
Information Service, Springfield VA 22151
Table 1: Cyclist Sample Sizes
No. of Cyclists&
Earned Points&
Points Lost
Palo Alto&
Table 2: Traffic Maneuvers With
Statistically-Significant Differences in Percent Defective Between Cities
&Population
&Traffic Signal
&Stop Sign
&Right Turn Only
&Intersection Approach
&Left Turn
&Lane Change
&Right Side of Moving Car
Table 3: Types of Errors, by Percent
Neither slowing nor looking
Not looking
Wrong start position & not looking
&Wrong start position
&Not looking
&LANE CHANGE
&Not looking
Table 4: Percent Defective and Statistical Significance
of the Differences
&Traffic Signal
Lane Change
Avoid Right-Turn-Only Lane
Intersection Approach
Right-hand Side of Moving Car
FORESTER CYCLING PROFICIENCY SCORE SHEET
Copyright John Forester,
Page 1 of 2
GROUP # _________________
CYCLIST # __________________
NAME _______________________________
DATE _______________________
ADDRESS _______________________________ TEST PLACE _____________________________
_______________________________
EXAMINER _____________SCORER ___________
Total Possible _________ Total Lost _________ Score (100(P - L)/P ______________
TRAFFIC SIGNAL .........+5____________
BEING OVERTAKEN......... +10 ___________
Wrong Action........ -5____________
Too Far Left........... -8___________
STOP SIGN.............. +5____________
Too Far Right.......... -4___________
Too Fast ............-2____________
OVERTAKING ...............+10__________
Not Looking .........-4____________
Swerving ...............-4___________
Not Yielding ........-5____________
No Look B4 Swerve ......-8___________
EXIT DRIVEWAY ..........+5____________
Cut Off Slow Driver ....-5___________
Too Fast ............-4____________
RIGHT TURN ................+5___________
Not Looking .........-4____________
Wrong Lane .............-2___________
Not Yielding ........-4____________
Not Yielding ...........-5___________
RIGHT TURN ONLY .......+10___________
Not Looking Left .......-4___________
Straight from RTOL ..-8____________
LEFT TURN ................+15___________
Swerving Out ........-8____________
Wrong Start Posit .....-12___________
INTERSECTION APPR'CH ..+10___________
Not Looking ...........-10___________
R-Side R-Turn Car ...-8____________
Not Yielding ..........-15___________
R-Side Moving Car ...-4____________
No Stop in Ped Turn ...-15___________
Too Far Right .......-4____________
End in Wrong Lane ......-5___________
Too Far Left ........-4____________
MULTIPLE L-TURN LANES ....+10___________
PARKED CAR ............+10___________
Wrong Lane Choice .......-7___________
Swerving ............-8___________
Wrong Side Of Lane ......-4___________
Too Far Out .........-2___________
CHANGING LANES ............+15___________
Too Close ...........-4___________
Not Looking .............-8___________
No Return When Req ..-2___________
Not Yielding ...........-12___________
Return When Not Req .-4___________
Too Many Lanes ..........-5___________
FORESTER CYCLING PROFICIENCY SCORE SHEET
Page 2 of 2
GROUP # __________________
CYCLIST # _________________
MERGE .................+15___________
PEDALLING ................+5___________
Incorrect Path ......-8___________
Slow Cadence ..........-2___________
Not Yielding .......-12___________
Stiff Ankling .........-2___________
DIVERGE ...............+15___________
SHIFTING .................+5___________
Incorrect Path ......-8___________
Too Slow on Hills .....-2___________
Not Looking .........-8___________
Too Slow in Traffic ...-2___________
Not Yielding .......-12___________
PANIC STOP ..............+20___________
GROUP RIDING ..........+15___________
Rear Wheel Skid .......-5___________
Overlap .............-5___________
Lift Rear Wheel .......-15___________
Too Far Behind ......-2___________
Skid & Fall ...........-15___________
Not Indicating Rock .-2___________
INSTANT TURN .............+20___________
Not Indicating Slow .-5___________
Too Wide ...............-5___________
Swerving ............-8___________
Too Slow ..............-10___________
WIDE TO NARROW .........+5___________
ROAD DEFECT ..............+20___________
Swerving ............-6___________
Incorrect Action ......-10___________
No Look or Yield ....-4___________
WIND BLAST ...............+20___________
OFF-ON ROADWAY ........+15___________
Too Much Wobble .......-10___________
Bad Choice of Place .-2___________
AVOID MOT. @ STOP SIGN ...+20___________
Too Fast Return .....-8____________
Incorrect .............-10___________
Not Looking .........-8___________
AVOID MOTORIST MERGE .....+20___________
Not Yielding ........-8___________
Incorrect ................-10___________
Not Perpendicular ...-8___________
AVOID MOT. RIGHT TURN ....+20___________
DIAGONAL RR TRACKS ....+15___________
Incorrect .............-10___________
Not Looking ........-12___________
AVOID MOT. LEFT TURN .....+20___________
Not Yielding .......-12___________
Incorrect Action ......-10___________
Not Perpendicular ..-10___________
POSTURE ................+5___________
Incorrect Saddle Ht .-2___________
Incorrect Foot Pos ..-2___________
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