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.

Paved shoulders

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)

Critical dimensions

Less 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:

• using rumble strips exclusively on limited access or controlled access facilities
• using a textured white fog line (Oregon) rather than rumble strips
• leaving gaps (12 feet in every 60 feet) between the rumbles to allow bicyclists to cross them if necessary

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.
http://www.dot.state.wi.us/dtim/pdf/bikeplan.pdf



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Wide Outside Lanes

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 street.

Critical dimensions

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 other obstacles.

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 conclusions:

• 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 scale.

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 include Dallas, Texas and North Carolina.



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Signed shared roadways

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 so designated:

• 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:

"Directional 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.

Critical issues

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).

• one-way, carrying bicyclists in the same direction as the adjacent travel lane
• on the right side of the roadway
• located between the parking lane (if there is one) and the travel lane

Bicycle lane width

4 feet (1.2m): minimum width of bike lane on roadways with no curb and gutter
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

6-inch (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. www.odot.state.or.us/techserv/bikewalk/planimag/restripn.htm

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 even less.

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
www.city.davis.ca.us/city/pworks/bike/bkwypn1.htm


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