Shared Lane Markings

Description

Shared Lane Markings (SLMs), or “sharrows,” are road markings used to indicate a shared lane environment for bicycles and automobiles. Among other benefits shared lane markings reinforce the legitimacy of bicycle traffic on the street,  recommend proper bicyclist positioning, and may be configured to offer directional and wayfinding guidance. The shared lane marking is not a facility type, it is a pavement marking with a variety of uses to support a complete bikeway network. The MUTCD outlines guidance for shared lane markings in section 9C.07.

Click on the images below to view 3D concepts of shared lane markings. The configurations shown are based on Portland, OR, and San Francisco, CA, examples.


Treatment details can be accessed below under design guidance.

Shared Lane Marking Benefits

  • Encourages bicyclists to position themselves safely in lanes too narrow for a motor vehicle and a bicycle to comfortably travel side by side within the same traffic lane.
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  • Alerts motor vehicle drivers to the potential presence of bicyclists.
  • Alerts road users of the lateral position bicyclists are expected to occupy within the travel lane.
  • Indicates a proper path for bicyclists through difficult or potentially hazardous situations, such as railroad tracks.
  • Advertises the presence of bikeway routes to all users.
  • Provides a wayfinding element along bike routes.
  • Demonstrated to increase the distance between bicyclists and parked cars, keeping bicyclists out of the “door zone.”
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  • Encourages safe passing by motorists.
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  • Requires no additional street space.
  • Reduces the incidence of sidewalk riding.
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  • Reduces the incidence of wrong-way bicycling.
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Typical Applications

As shared lane markings are a relatively new bikeway marking in American cities, guidance on application will continue to evolve over time. Shared lane markings should not be considered a substitute for bike lanes, cycle tracks, or other separation treatments where these types of facilities are otherwise warranted or space permits. Shared lane markings can be used as a standard element in the development of bicycle boulevards to identify streets as bikeways and to provide wayfinding along the route.

Desirable shared lane marking applications:

  • To indicate a shared lane situation where the speed differential between bicyclist and motorist travel speeds is very low, such as:
On bicycle boulevards or similar low volume, traffic calmed, shared streets with a designed speed of < 25 mph. On downhill segments, preferably paired with an uphill bike lane.  If space permits, consider a wide downhill bike lane. On streets where the traffic signals are timed for a bicycling travel speed of 12 to 15 miles per hour.
  • As a reasonable alternative to a bike lane:
Where street width can only accommodate a bicycle lane in one direction. On hills, lanes should be provided in the uphill direction. Within single or multi-lane roundabouts.
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Along front-in angled parking, where a bike lane is undesirable.
  • To strengthen connections in a bikeway network:
To fill a gap in an otherwise continuous bike path or bike lane, generally for a short distance. To transition bicyclists across traffic lanes or from conventional bike lanes or cycle tracks to a shared lane environment. To direct bicyclists along circuitous routes.
  • To clarify bicyclist movement and positioning in challenging environments:
To designate movement and positioning of bicycles through intersections. To designate movement and positioning of bicyclists through a combined bike lane/turn lane. To assist bicyclists in taking the lane in the presence of a double turn lanes. Double turn lanes are undesirable for bicyclists.
In the street alongside separated bikeway facilities such as cycle tracks, to permit continued use of the street by bicyclists who prefer to ride in the street.
  • Generally, not appropriate on streets that have a speed limit above 35 mph.
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Design Guidance

Required Features
The Shared Lane Marking in use within the United States is the bike-and-chevron “sharrow,” illustrated in MUTCD figure 9C-9.
Shared Lane Markings shall not be used on shoulders,  in designated bicycle lanes, or to designate bicycle detection at signalized intersections. (MUTCD 9C.07 03)
Recommended Features
Frequent, visible placement of markings is essential. The number of markings along a street should correspond to the difficulty bicyclists experience taking the proper travel path or position. SLMs used to bridge discontinuous bicycle facilities or along busier streets should be placed more frequently (50 to 100 feet) than along low traffic bicycle routes (up to 250 feet or more). SLMs used along low volume routes can be staggered by direction to provide markings closer together.
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Lateral placement is critical to encourage riders to avoid the “door zone” and to encourage safe passing behavior. MUTCD guidance recommends minimum placement when a parking lane is present at 11 feet from the curb face.
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On streets with posted 25 mph speeds or slower, preferred placement is in the center of the travel lane to minimize wear and encourage bicyclists to occupy the full travel lane.
On streets with posted 35 mph speeds or faster and motor vehicle volumes higher than 3,000 vpd shared lane markings are not a preferred treatment. On these streets other bikeway types are preferred.
If on-street vehicle parking is not present, SLMs should be placed far enough from the curb to direct bicyclists away from gutters, seams, and other obstacles. On streets with posted 25 mph speeds or slower, preferred placement is in the center of the travel lane to minimize wear and encourage bicyclists to occupy the full travel lane. MUTCD guidance recommends minimum placement with no parking at 4 feet from the curb face.
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Optional Features
For wayfinding purposes the orientation of the chevron marking may be adjusted to direct bicyclists along discontinuous routes.
Color may be used to enhance the visibility of the shared lane marking and to further encourage desired lane positioning.
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Dotted line markings may accompany the shared lane marking to further encourage desired lane positioning.
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Maintenance

  • Frequent, visible placement of markings is essential.
  • Lateral placement is critical to encourage riders to avoid the “door zone.”
  • The shared lane marking may be placed in the center of the lane between wheel treads to minimize wear.

Treatment Adoption and Professional Consensus

  • Used by at least 76 jurisdictions in 26 States as of 2009, including most NACTO member cities.

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Reference Publications