||John S. Allen
7 University Park
Waltham, MA 02154-1523
(617) 891-9307 voice/fax
Technical writing, translation
Mechanical design, acoustics
Consultant on bicycling
Effective Cycling instructor
Cambridge bicycle policy draft statement
by John Allen
Originally submitted July 1995; revised version of January 17,
In general: I think this document makes a good and positive statement, but there are
many technical details that need refinementso read on! You may assume that I agree
with and support sections on which I do not comment.
p. 5 Statement about reduced number of costly accidents and property
damage is only partly true, since the risk of injuries and fatalities per mile of travel
is greater for bicycling than for public transportation or private motor vehicles (except
motorcycles). What can be stated truthfully and positively is that the health benefits of
bicycling greatly outweigh the accident risk, that bicycling is safer than inline skating
or walking per mile of travel, and that the risk per hour of exposure is about the same
for bicycling, motoring or walking.
The words modifying the existing street system to rededicate some of the space to
nonmotorized modes open the entire Pandoras box of bike lane design issues. In
most cases, shared us of road space is more practical, with wide outside lanes open to
both bicyclists and motorists.
The statement that a person in reasonable physical condition can ride a bicycle
up to at least three miles -- five miles is considered reasonable bicycling distance --
with minimal physical exertion is confusing. Generally, bicycling is as strenuous as
walking at 1/3 the speed. At 10 mph, bicycling is no more strenuous than walking. Anyone
except a very old or infirm person who rides a bicycle regularly enough to get minimal
training can maintain 15 mph for hours. The limit on bicycling distances is not physical
capacity but available time.
p. 6 people have repeatedly stated their desire for more and
better bikeways (and walkways. Most people dont know what a better bikeway is.
Following their wishes has led to the great majority of bikeways being poorly
designed and located.
Rodale study was conducted in 1990, not 1992.
p. 8 again shows a strong bike lane bias without spelling out what is
an acceptable bike lane. The bias here is to promote bicycle use, not necessarily to build
p. 9 The Worldwatch pamphlet by Marcia Lowe has been devastatingly
analysed by John Forester. He maintains that most of what it says is untrue even if it
Here the Rodale study is cited as being from 1991. This is probably the publication
date rather than the time research was conducted. This study has been republished by the
US CPSC in its Bicycle Use and Hazard Patterns in the United States (1995).
p. 10 and 11 The definitions here are not those under Massachusetts
law and regulations. See Chapter 90 definitions, 720 CMR definitions and 350 CMR (MDC)
The definition of bicycle here is awkward and much less good than the one
under Mass. law, which stresses the pedal power aspect, is inclusive of tricycles
including adult tricycles and avoids the confusing wheel size issue.
The definition of bikeway is misleading, because there are very few
bikeways from which pedestrians are excluded, as a practical matter. The only
exception that works at all is when a pedestrian path parallels a bicycle path as in
Definition of MUTCD refers to State of Massachusetts. Massachusetts is a
Commonwealth, not a state.
The definition of vehicle is quite unlike the one in 720 CMR or 350 CMR.
Also, Massachusetts uses some unique terminology about roadway and right of way.
p. 13 Under the heading Motor Vehicle-bicycle crash
summary, we read that approximately 75% of bicycle crashes do not involve motor
vehicles. What is the source for this? Every study Ive seen puts the percentage
between 80 and 90%.
Then the section on accidents goes on to discuss almost nothing but bicycle-motor
vehicle collisions. Shouldnt we be as concerned about the other 80 to 90 percent of
crashes? Dont they matter?
Colorado Dept. of Transportation draft design guidelines: do the conclusions here
reflect original research? They seem to be drawn from the classic Cross and Fisher study
from around 1980. Note that the CTPS conducted a study about 10 years ago in the Boston
area which closely confirmed Cross and Fisher. Cathy Lewis has details. This document
should cite it.
The Colorado statistics do agree with Cross and Fisher about the two accident types
which are made more likely by bike lanes.
University of North Carolina: this analysis appears to reflect original research.
However, some of the statistics lack context at least as presented here. The accident rate
on different types of roads, or with on-street parking, can not be determined without
knowing the amount of riding there. When referring to alcohol use, is this by the cyclist
or by a motorist who struck the cyclist or a pedestrian who staggered out in front of the
cyclist? Another recent study from Johns Hopkins University shows that a high percentage
of fatal cycling accidents involved drunk cyclists!
p. 14 Oregon State Bicycle Plan: this detailed analysis treats only
the 10-20% of bicycle crashes that involve a car. Also note (p. 15) the contradiction
between the first and second paragraph as to who is at fault, and in the third, the term
invisible to cars. Bicyclists are never visible to cars since cars cant
see. Generally, their drivers can, or else they would run into something before they even
got out of the driveway. The confusion of cars with their drivers is a very common one,
typical of people who do not think clearly as bicyclists about how drivers interact with
them. It is a strong symptom of what John Forester calls the cyclist inferiority
p. 16 The conclusion that bikeways increase safety and traffic law
compliance in Eugene and Corvallis, Oregon is not justified here. Simply juxtaposing the
facts that accident rates are lower and that there are bikeways does not lead to this
conclusion. Couldnt education and law enforcement in these bike-conscious towns have
some effect? France has very few separate bicycle facilities, yet all bicyclists obey the
rules of the road. That is because they are taught in elementary school and they are
enforced. The careful Wachtel and Lewiston study in the September, 1994 ITE Journal shows
no measureable effect of bike lanes on safety.
p. 17 should say: Providing shoulders of equal width and quality
on each side of the road.
p. 18: the section on Hazards of routing cyclists off
thoroughfares onto less-traveled streets is easily read as a justification not to
improve cycling conditions on secondary streets. This is where most people live and most
children ride. I treat this topic in more detail in my statement of January 17, 1995 to
p. 19 Definition under Brakes doesnt reflect
Massachusetts law, and is not technically correct, since the front brake can lock but not
skid the wheel on dry pavement.
Definition under Lights seems to say that white reflectors are used on the
rear. A red reflector or taillamp is what the law requires.
p. 20 Now once again we say that most bicycle crashes do not involve
motor vehicles. But there has been no discussion in this section of how facilities can
help prevent other types of crashes e.g. bike-bike, bike-ped and single-bike.
Research (Harborview Medical Center, Seattle) shows that helmets reduce head injuries
by 88% and brain injuries by 85%, not up to 80%.
All in all: this section is built on a weak foundation, does not discuss 80 to 90% of
accidents, and could do well by referring to some of the classic studies such as Cross and
Fisher, Kaplan, Chlapecka, Shupack and DriessenForester summarizes some of them in
his section on bicycle accidents in Effective Cycling (MIT Press).
p. 21 Im not comfortable with the idea that bike lanes are
to be provided wherever possible. for several reasons.
1) Double-parking conflicts and bicyclists being made a
scapegoat for increased enforcement against double parking. This is a great way to make
enemies for a bicycle program.
2) The idea that if there is a bike lane, that is the only place
bicyclists should ride. Especially troublesome in combination with double-parking in the
3) Intersection conflicts and misunderstandings, most commonly
bicyclist left turn from right lane and motorist right turn from center lane. Bike lane
stripes must be dashed or dropped before intersections.
All in all, Id prefer undesignated guide stripes or wide outside lanes in most
places. Bike lanes can make sense in some, such as on bridges or in other long stretches
without cross streets or driveways.
p. 23 refers to Massachusetts State Law. In fact, bicycles
are defined as vehicles in the Commonwealth of Massachusetts Regulations 350 and 720.
Also, where bicycles are prohibited is explicitly spelled out in the regulations and also
in the Statutes (Chapter 85, section 11B) as only on limited-access or express state
highways, which must by definition be divided highways, generally with grade separations
at intersections, and where signs are posted. In other words, bicycles may not be
prohibited anywhere in Cambridge except maybe on parts of Memorial Drive, the McClellan
Highway, and Route 2. In practice, bicycle prohibitions are not posted there, either.
A wide outside lane that accommodates both cyclists and motor vehicles is one way
of designating a shared roadway. It is also often one way of improving a shared
roadway either by widening it or by restriping. These lanes should be provided where
there is inadequate width to provide bike lanes. Once again, this documents
astonishing pro bike lane bias surfaces. Many, and especially cyclists, would argue that a
wide outside lane (perhaps with guide lines but not specially designated for bicycles) is
preferable to a bike lane under most conditions for a number of reasons, in particular
because a wide outside lane provides the same amount of additional travel space without
creating confusion about the traffic rules: read on.
p. 24 The appropriate facilities for bicyclists are bike lanes
on urban arterial and collector streets. This is a very sweeping and one-sided
statement with which many cyclists strongly disagree and which is open to serious
scientific questioning. Wachtel and Lewiston (ITE Journal, Sept. 1994) show no difference
in accident rates between bike lane and non-bike lane arterials. Theres also the
question of placing all your political eggs in this one basket, which has resulted in
political failure e.g. in New York. The issue of bike lanes has been thoroughly studied
and debated in California, where they have been in place for 20 years. Lets benefit
from what has been learned there. Consider the following comments a counterbalance to the
heavy pro-bike lane bias of the draft document. I am not opposed to bike lanes where
appropriate, but lets be reasonable about them, not discuss them as if they were
paved with gold.
Most of the statements in support of bike lanes in this section are false or only
Bike lanes are appropriate on minor collector or local streets if traffic speeds
and volumes are higher than...25 MPH or ADT over 3000. The justification for bike
lanes depends also on the volume of bicycle traffic. A designated bike lane is required to
be 4 to 6 feet wide because the engineering assumption is that the bike lane must be wide
enough for 2 bikes, one passing another. That way, bikes going straight through never have
to use any other lane. That approach makes sense when motor traffic is very heavy and fast
and bicycle traffic is also heavy, but, considering the need to add 4 to 12 feet of
additional pavement or to remove it from other uses, is very costly under less demanding
conditions. Bicyclists can find opportunities to overtake without having a lane all their
own. On most Cambridge local and collector streets, bike lanes would require removing
either a travel lane or a parking lane. This an expedient which should be used with
discretion, where unavoidable, to avoid political repercussions.
Bike lanes help define the road space: true. But the definition provided is
...provide bicyclists with a path free of obstructions: untrue. This is
accomplished by strict law enforcement against double parking, not by lane striping.
Parking in bike lanes is an endemic problem where enforcement is less than strict. Illegal
parking is an endemic reality and serves the unavoidable need for businesses to receive
deliveries. Eliminating parking in bike lanes in Cambridge would create such a reaction
from the business community as you would not believe.
...decrease the stress level of bicyclists riding in traffic: true, as long
as the bike lanes can be kept clear of obstructions, and as long as the bicyclist is not
attempting to overtake or turn left in a travel lane narrowed by a bike lane on its right.
...Encourage bicyclists to ride in the correct designated roadway position:
True if they are going slower than other traffic and not turning left, and going the right
way. Bike lanes have been shown to encourage wrong-way riding, however.
...and signal motorists that cyclists have a right to the road: This is
simply untrue. Bike lanes signal motorists that bicyclists have a right to the bike lane,
and no right to the rest of the road. This becomes particularly onerous when, as often
follows, laws or ordinances are passed that eliminate or decrease bicyclists right
to the rest of the road. The first question an insurance company lawyer asks when a
bicyclist was injured on a bike lane street is was the bicyclist in the bike
lane. If not, the case is very rarely winnable before a jury even if the bicyclist
was legally in the right.
Bike lanes are intended to promote an orderly flow of traffic, by establishing
lines of demarcation... This is a waffling statement: it does not say that bike
lanes actually do promote an orderly flow of traffic. The standard traffic principles are
channelization by speed between intersections, and channelization by destination at
intersections. In fact, the bike lane system conflicts with the ordinary rules of the road
under the following conditions: motorist turning right; bicyclist turning left; bicyclist
Bike lane stripes can increase bicyclists confidence... So can guide
stripes without a designated bike lane, but no claim for this was made in the earlier
section. Lets be consistent. This is an argument for striping, not for 4 to
6 bike lanes.
Likewise...passing motorists are less likely to swerve toward opposing
traffic... This statement should not be made without a research citation. In
practice, the need of motorists to swerve toward opposing traffic depends fundamentally on
the motorists expectation of cyclist behavior and the width of the road. Cyclist
behavior varies. Where cyclists ride predictably, motorists dont give them
unnecessary room, bike lane or no bike lane. This is more a problem of education than of
engineering, in my opinionreinforced by riding in France, where cyclists ride
predictably. In any case, motorists are required to drive closer to opposing traffic by a
bike lane even when no bicycles are present. This inflexibility, taking discretion out of
the drivers hands and making it law, also can lead to crashes.
NB: The presence of a bicycle lane does not preclude the bicyclists from riding
in the motor vehicle travel lane if the situation warrants... . Even if this rule is
codified in the law and understood and observed in the community, most bike lanes on
Cambridge streets would have to be constructed by narrowing or removing travel lanes, not
by adding pavement width. Therefore the maneuvers which must be made using the travel
laneovertaking and preparing a left turnmay become more difficult and
dangerous. As a practical matter, a redneck attitude toward bicyclists is very common in
the US, and many motorists will be angry to see bicyclists anywhere except in the bike
lane. Besides, this misstates the law. There is no such thing as a motor vehicle lane. The
lanes other than the bike lane are as open to bicyclists as to motorists under
they establish the correct position of bicyclists on the roadway
Establish ? The law, not lane lines, establishes this particularly in the
light of what Ive just said. Delineate, perhaps, and sometimes a correct position
(there is no single correct position), sometimes an incorrect one.
They promote an orderly flow of traffic They may increase order in some
ways but they increase disorder in others, as discussed above.
they allow bicyclist to pass motor vehicles stopped at a signal (coming up to the
stop line, and also stopping for the signal). Motorist right turn in front of
bicyclist is one of the top 2 or 3 causes of bicycle accidents, as cited on page 13 of
this same document and mentioned again on p. 26.. Bicyclists should never come up to the
stop line at an intersection where right turns are permitted. Facilities certainly should
not encourage this.
they send a message to motorists that bicyclists have a right to the
roadway. Im sorry to have to say so, but this is sophistry. As discussed
above, they send a message that bicyclists have a right to the bike lane.
they remind motorists to look for bicyclists on the road Once again, we
have a solution looking for a problem. It could as easily be stated that bike lanes let
motorists be heedless of bicyclists anywhere except in the bike lane, because motorists
assume that all bicyclists will be in the bike lane.
they give bicyclists a clear place to be so they are not tempted to ride on the
sidewalk True, but that doesnt mean that bicyclists can simply ride in the
bike lane and not have to learn correct maneuvering according to the rules of the road.
Bike lanes, as discussed above, can encourage bicyclists to make incorrect maneuvers.
There is no solution that eliminates cyclists need to be knowledgeable and to take
responsibility for their own safety.
reverse of p. 26: note that intersection diagram shows motorist merging into the bike
lane to make right turn, contrary to what Cara Seiderman has advocated.
p. 26 a two-legged right turn... fails to state that this
can be made in safety only by coming to a full stop at the far corner of the intersection.
It is also desirable that detectors in left-turn lanes be sensitive enough to
detect bicycles...At intersections without bike lanes, it is desirable to install
detectors that are sensitive enough to detect bicycles. The acknowledgment that
detectors should detect bicycles is welcome. But it is not only desirable. It is mandated
by the law which defines bicycles as vehicles.
p. 27 Treatment of bike paths is too dismissive. There are several
existing bike paths in Cambridge and others proposed e.g. Watertown Branch, Alewife Brook
Parkway, Charles River Park extension, railbed between Vassar Street and Albany Street..
Existing paths need improvements, and these should be discussed, as well as details of
design for proposed ones.
Treatment of traffic calming should be much more detailed, with examples. In
particular, this report should address the issue of replacing conflicting one-way signs
with other traffic calming measures which are more bicycle-friendly. This is a key element
to improving bicycle friendliness of Cambridges residential neighborhoods.
p. 29 Right turn only lanes: The same principles that apply to right
turn only lanes also apply anywhere motorists may turn right -- any intersection or
driveway. This is the Achilles Heel of the bike lane approach. To warn against the
right turn problem only where there is a designated right turn lane is inconsistent.
p. 30 50 foot dashed length before intersections is far too short to
allow a proper merge.
p. 32 Loop and other detectors not only should be tuned and
retuned to detect bicycles. They should be designed to detect bicycles, using
quadrupole or California D-type loops.
Bike path-road crossings are one important location for bicycle specific signals which
is not mentioned.
Assuring the sensitivity of existing loop detectors to detect cyclists.
These are not just improvements that can be made but are mandated by the
definition of bicycles as vehicles.
Inset before p. 34: Railing shown is of poor design for bicycles, with
vertical bars rather than horizontal rub strip, opaque through curve and not set back from
inside of curve (bicycles lean to inside of curve).
Appendix F List of statutes cited is incomplete. See the index to the
statutes for a complete list. I have a reasonably complete collection of statutes in a
notebook. Also, regulations, particularly sections 350 and 720, bear directly on
bicycling. Section should also include Cambridge ordinances relative to bicycling, not
just parking ordinance.
References This list of references is heavy on speculative studies and
light on basic research works. Many important references in the field of bicycle traffic
engineering and accident studies are missing. I have mentioned some in my comments. More
balance in references would reflect a more balanced presentation is several areas, notably
accidents and facility types.