Paved shoulders | Wide outside lanes | Signed shared roads | Bike lanes | Innovative bike lane designs
can be found on almost every type of roadway, from rural interstates
to local streets, and the majority of these roads have no special
facilities designated for bicycling. Nonetheless, they are a critical
part of the bicycling infrastructure and need to be maintained and
operated so that bicyclists can use them safely and comfortably. Drainage
grates, railroad tracks, potholes, utility covers, gravel, wet leaves,
pavement joints and many other surface irregularities have a profound
impact on bicyclists and can quickly cause a fall and serious injury.
In Basic Improvements for Bicyclists (www.bikeplan.com)
, author John Williams has updated Improving Local Conditions for
Bicycling, a useful summary of some of the strategies for implementing
simple, low-cost improvements to overcome hazards such as these,
regardless of the type of roadway.
The AASHTO Guide for the Development of Bicycle Facilities notes
that in rural areas "adding or improving paved shoulders often can
be the best way to accommodate bicyclists" – and they have the additional
attraction of providing a variety of benefits to motorists and other
road users as well. (www.odot.state.or.us/techserv/bikewalk/whyhave.htm)
than 4 feet (1.2m): any additional width of paved shoulder is better
than none at all, but below 4 feet a shoulder should not be designated
or marked as a bicycle facility.
4 feet (1.2m): minimum width to accommodate bicycle travel measurement
must be of useable width and should NOT include the gutter pan or
any area treated with rumble strips
5 feet (1.5m) or more: minimum width recommended from the face of
a guardrail, curb or other barrier
Widths should be increased with higher bicycle usage, motor vehicle
speeds above 50mi/hr, higher percentage of truck and bus traffic.
Further guidance on the appropriate width of shoulders to accommodate
bicyclists on roadways in these situations can be found in FHWA's
Selecting Roadway Design Treatments to Accommodate Bicyclists.
Critical issues and Frequently Asked Questions
When should I designate a shoulder as a bikeway?
Paved shoulders, whether they are designated and signed as bikeways
or not, provide a great place for people to ride. Most states do not
designate or mark their paved shoulders as bikeways, but some do,
such as Oregon. Paved shoulders should not be designated or marked
as bikeways unless they meet the width guidelines shown above (4 feet
or 5 feet from a barrier or railing) and have rideable width free
from obstructions or treatments such as rumble strips (see below).
Oregon usually designates shoulder bikeways if they are a minimum
of six feet wide, while Florida sets five feet as their minimum.
Designating a shoulder as a bikeway may also be useful to provide
guidance to cyclists following a particular route (e.g. between two
trails, or other popular destinations for bicyclists). The advice
on signed shared roadways should be followed.
I have heard that the installation of rumble strips on paved shoulders
is an issue. How can it be resolved?
There's no question that rumble strips are effective in alerting sleepy
or inattentive drivers and that their use has positive safety benefits.
However, it's equally true that none of the current designs for rumble
strips can be considered "bicycle safe" and that the use of rumble
strips can render a shoulder unusable for bicycling. The AASHTO bicycle
guide recommends that rumble strips not be used on routes used by
bicyclists unless a minimum of four feet of rideable surface remains
for the bicyclist (five feet from a curb or guardrail). Other policies
that have balanced the needs of motorists and bicyclists include:
For more information on rumble strips visit:
- using rumble strips exclusively on limited access or controlled
- using a textured white fog line (Oregon) rather than rumble
- leaving gaps (12 feet in every 60 feet) between the rumbles
to allow bicyclists to cross them if necessary
FHWA's resource site at
A bicycle user group's perspective at http://bicyclecolo.org/site/page.cfm?PageID=49
Places to See:
Wisconsin DOT has a policy of providing a three foot paved shoulder
on all highways with an average daily traffic in excess of 1,000
vehicles, and this is widened to five feet if a moderate number
of bicyclists regularly use the road. See page 38 of the WisDOT
State Bicycle Plan.
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In urban areas, paved shoulders are not normally provided on major
roads. A wider outside (or curbside) lane allows a motorist to safely
pass a cyclist while remaining in the same lane and this can be
a significant benefit and improvement for cyclists, especially more
experienced riders. A wider outside lane also helps trucks, buses,
and vehicles turning onto the major road from a driveway or wide
14 feet (4.2m): recommended width for wide outside lane width must
be useable and measurement should be from the edge line or joint
of the gutter pan to the lane line
15 feet: (4.5m) preferred where extra space required for maneuvering
(e.g. on steep grades) or to keep clear of on-street parking or
Continuous stretches of lane 15 feet or wider may encourage the
undesirable operation of two motor vehicles in one lane. Where this
much width is available, consideration should be given to striping
bike lanes or shoulders.
Critical issues and Frequently Asked Questions
Is a wide outside lane safer/better than striping a bicycle lane?
The simple answer is that there have been too few studies to answer
this question definitively, but the studies that have been done suggest
that while there may be no direct affect on safety, both bicyclists
AND motorists are more comfortable and confident on roads with striped
bike lanes. In An Evaluation of Shared-use Facilities for Bicycles
and Motor Vehicles, by David Harkey and Richard Stewart, the authors
updated studies from the 1970s investigating the interaction of motorists
and bicyclists in different roadway conditions and came to the following
- motorists are less likely to encroach on the adjacent lane when they are passing a bicyclist on facilities with pave shoulders or bicycle lanes
- motorists have less variation in their lane placement when they are passing a bicyclist on a paved shoulder or bicycle lane facility
- bicyclists are more likely to ride further from the edge of the roadway in a bicycle lane or on a paved shoulder than they do in a wide curb lane (providing a greater margin of safety to avoid obstacles and making them more visible)
Two studies of "levels of service" for bicyclists also provide useful
insight into answering this question.
In Real Time Human Perceptions: Towards
a Bicycle Level of Service, by Landis, Vattikuti, and Brannick,
the authors have developed a level of service model for bicyclists
that incorporates cyclists' perceptions and feelings of comfort
and safety. In studying the impact of striping a bike lane or a
paved shoulder the authors fund that increasing the width of a travel
lane to 16 feet increased the level of service to the bicyclist
by 13 percent. By striping a four foot bike lane on the same roadway,
the level of service increased by 31 percent.
Development of the Bicycle Compatibility Index: A Level of Service
Concept, Final Report, by Harkey, Reinfurt, Knuiman, Stewart,
and Sorton. The Bicycle Compatibility Index incorporates the geometric
and operational variables considered by adult bicyclists to be important
in terms of their comfort level when riding on the streets with
motor vehicles. The authors note that the variable with the largest
effect on the index is the presence or absence of a bicycle lane
or paved shoulder that is at least 0.9m wide. Striping a bike lane
reduced bicyclist stress levels by almost one unit on a five unit
Link: Florida DOT web site, http://www11.myflorida.com/safety/ped_bike/handbooks_and_research/bhchpt4.pdf
Can I provide a wider outside lane by reducing the width of other
travel or turning lanes?
The simple answer to this one is, "yes." The AASHTO bicycle guide
says "restriping to provide wide curb lanes may also be considered
on some multi-lane facilities by making the remaining travel lanes
and left turn lanes narrower." The guide does caution you, however,
to do this only after careful consideration of traffic characteristics
and other factors. So, for example, a relatively low volume road
with two 12 foot travel lanes (in one direction) could be restriped
with a 13/11 foot or 14/10 foot pattern without adding anything
to the width of the roadway.
Places to See:
Some states and communities have decided that wide outside lanes
are the primary way in which they will accommodate bicyclists. These
Texas and North Carolina.
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The AASHTO Guide describes signed shared roadways (bike routes)
as "those that have been identified by signing as preferred bike
routes" and goes on to describe the reasons why routes might be
continuity between bicycle lanes, trails or other bicycle facilities
marking a common route for bicyclists through a high demand corridor
directing cyclists to low volume roads or those with a paved shoulder
directing cyclists to particular destinations (e.g. park, school
or commercial district)
In addition, designation indicates that there are particular advantages
to using the route rather than an alternative. Signed shared roadways
generally do not succeed in diverting cyclists away from routes
that are more direct, faster, and more convenient even though they
may be on quieter streets. Indeed, the Oregon DOT bicycle manual
graphically shows how such efforts can actually create greater danger
and inconvenience for bicyclists by requiring them to cross major
roads just to use a designated bicycle route. ODOT goes on to say:
signs are useful where it is recommended that bicyclists follow
a routing that differs from the routing recommended for motorists.
This may be for reasons of safety, convenience, or because bicyclists
are banned from a section of roadway (the routing must have obvious
advantages over other routes).
"ODOT recommends against the use of BIKE ROUTE signs and arrows
along city streets with no indication to cyclists as to where they
are being directed. Cyclists will usually ignore these signs if
they send them out of direction."
The AASHTO guide recommends considering a number of factors before
signing a route
the route provides through and direct travel
the route connects discontinuous segments of shared use paths
or bike lanes
bicyclists are given greater priority on the signed route than
on the alternate route
street parking has been removed or limited to provide more width
a smooth surface has been provided
regular street sweeping and maintenance is assured
wider curb lanes are provided compare to parallel roads
shoulders are at least four feet wide
In all cases, shared use roadway signing should include information
on distance, direction and destination, and should not end at a
barrier such as a major intersection or narrow bridge.
Q. How often should I sign a shared signed roadway?
A. The AASHTO Guide recommends signing a shared signed roadway every
1/4 mile (500m) and at every turn (both to mark the turn and to
confirm that the rider has made the correct turn).
Places to See:
New York State DOT
City of Denver
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Bike lanes are defined as "a portion of the roadway which has been
designated by striping , signing and pavement marking for the preferential
or exclusive use by bicyclists". Bicycle lanes make the movements
of both motorists and bicyclists more predictable and as with other
bicycle facilities there are advantages to all road users in striping
them on the roadway.
Bicycle-friendly cities such as Madison, Eugene, Davis, Gainesville,
and Palo Alto have developed extensive bike lane networks since the
1970s and more recently large cities such as Tucson, Chicago, Houston,
Philadelphia, Portland and Seattle have begun to stripe bike lanes
on their arterial and collector streets as a way of encouraging bicycle
In general, bicycle lanes should always be:
one-way, carrying bicyclists in the same direction as the adjacent
on the right side of the roadway
located between the parking lane (if there is one) and the travel
Bicycle lane width
4 feet (1.2m): minimum width of bike lane on roadways with no curb
5 feet (1.5m): minimum width of bike lane when adjacent to parking,
from the face of the curb or guardrail
11 feet (3.3m): shared bike lane and parking area, no curb face
12 feet (3.6m): shared bike lane and parking area with a curb face
Bicycle lane stripe width
(150mm): solid white line separating bike lane from motor vehicle
lane (maybe raised to 8-inches (200mm) for emphasis
4-inch (100mm): optional solid white line separating the bike lane
from parking spaces
Q. How can I fit bike lanes onto a 44ft wide urban road?
A. The City of Chicago, among others, is successfully striping 44ft
roadways with two seven foot parking lanes, two five foot bike lanes
and two ten foot travel lanes.
Q. My city engineer says he can't reduce travel lanes below the
AASHTO recommended width of 12 feet. Is that true?
A. No. In fact, the new AASHTO Guide for the Development of Bicycle
Facilities says "another important reason for constructing bike
lanes is to better accommodate bicyclists where insufficient space
exists for comfortable riding on existing streets. This may be accomplished
by reducing the width of vehicular lanes or prohibiting parking...".
The Oregon Department of Transportation bicycle plan has an extensive
section on restriping existing streets to incorporate bike lanes.
Q. I am not sure a white paint line is enough. Can I use raised
pavement markers or some kind of barrier or curb to separate the
bike lane from motor vehicles?
A. Studies have shown that a simple white line is actually quite
effective in channelizing both motorists and bicyclists and that
both feel more comfortable with the line in place. Raised pavement
markers can cause a cyclist to lose control and fall; barriers and
curbs also prevent bicyclists from avoiding obstacles (or even passing
another cyclist) and making a left turn, and make maintenance much
more challenging (and unlikely).
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Innovative bike lane designs
There are a number of innovative bike lane designs that have been
tried and tested to overcome particular barriers to bicycling, or
to solve a problem in a particular location.
Counter-flow bike lanes
While bike lanes should normally carry
bicyclists in the direction of traffic, there are some locations
where there is a strong demand for bicyclists to travel against
the normal flow of traffic, or to travel in both directions on a
one-way street. For example, University Avenue in Madison, Wis.,
runs through the heart of the University of Wisconsin campus can
carries heavy flows of bicyclists and other road users. Because
of the high demand for bicycle travel in both directions, several
years ago the road was rebuilt with a bus lane, bike lane and three
travel lanes in one direction and a bike lane only (separated by
a raised median) in the other direction.
A number of communities have created short segments of counter-flow bike
lanes in order to provide bicyclists unique access to residential streets.
For example, the cities of Madison and Portland have both used this technique
to open up a network of routes on residential streets that are not accessible in both directions both motor vehicle essentially creating a very short stretch of roadway that is two-way for bikes but only one-way for cars.
Colored bike lanes
Colored bike lanes have been a feature of bicycle infrastructure
in the Netherlands (red), Denmark (blue), France (green) and many
other countries for many years. In the United Kingdom, both red
and green pigments are used to delineate bike lanes and bike boxes.
However, in this country their use has been limited to a few experiments
in just a handful of locations. The most extensive trial took
place in Portland, Ore., where a number of critical intersections
had blue bike lanes marked through them and the results were carefully
monitored. The results of the study can be found here.
Shared bike and bus lanes
A growing number of communities are using shared bus and bike lanes
to give preferential treatment to both bikes and public transport.
Examples currently include Tucson, Ariz.; Madison, Wis.; Toronto,
Ontario; Vancouver, BC; and Philadelphia, Pa. Often the lanes are
also able to be used by taxis and right-turning vehicles. Because
buses and bikes will pass each other in these lanes, lane width
is an important issue. The city of Madison likes to use 16 foot
lanes to allow a clear three feet of separation between the bicyclist
and a passing bus, but if either bus or bike traffic is light and
space is limited the width of a shared lane might be 14 feet or
Bike lanes on the left side of one-way streets
The city of Minneapolis recently striped a network of bike lanes
in the downtown area, but striped the lanes mostly on the left side
of one way streets (reasoning that cyclists therefore don't have
to contend with as many car doors being opened in front of them
or buses discharging passengers). They have developed the appropriate
signs and marking to warn motorists about turning left in front
of bicyclists traveling straight ahead. The city of Madison has
used similar left-side bike lanes on streets with a heavy percentage
of left-turning bicyclists but does not use them as a general rule.
Dimensions for left-side bike lanes should follow the guidelines
for bike lanes on the right side of streets.
Places to See:
City of Davis, Calif