Monday, May 7, 2012
 

VDOT guidance on use of sharrows

VDOT recently issued guidance on use of the Shared Lane Markings (sharrows) and Bicycles May Use Full Lane signs (BMUFL) in the Northern Virginia District. The formal title is BIKES MAY USE FULL LANE Signs and Shared Lane Markings, Northern Region Traffic Engineering Practice. It was written by Randy Dittberner, VDOT Traffic Engineer and dated April 10, 2012.

The guidance is meant to clarify how the devices should be used in our area. This is an important step in the implementation of these devices. We've heard that both devices will be installed on a few roads in Fairfax in the coming weeks. There will also be publicity to inform the public about why the devices are being used and what they mean.

From the guidance:
GENERAL CONSIDERATIONS

In order for these devices to be effective, they must not be overused, but rather limited to the locations where motor vehicle traffic, bicycle traffic, and roadway conditions combine to create the greatest need. As such, the following considerations apply when evaluating a roadway for the possible application of these devices:
  • Neither device shall be used on roadway segments with bike lanes, since a bike lane eliminates the need for these devices.
  • Neither device shall be used on roadway segments with paved shoulders 4 feet or more in width. Although cyclists are permitted to use the travel lane even where shoulders are present, these devices may inappropriately discourage some cyclists from using the shoulder.
  • Both devices should be limited to roadway segments designated by the local jurisdiction’s bicycle plan as part of its bicycle network.
  • Roadway segments with low traffic volume, less than 3,000 vehicles per day, should not need these devices, because they usually offer a sufficient cycling environment.
  • Neither device should be used on roadway segments with traffic volume greater than 30,000 vehicles per day or speed limits greater than 35 mph. Cyclists are generally permitted to use high-volume, high-speed roadways, but these devices may encourage novice cyclists to travel on a roadway above their skill level.
  • Both devices should be limited to roadway segments where travel lanes are delineated with longitudinal pavement markings or other methods. (Neither device should be used on undivided unmarked roadways.)
There is also specific guidance for the signs and sharrows:
BIKES MAY USE FULL LANE SIGN

BIKES MAY USE FULL LANE signs shall be used only where bicyclists are permitted by the Code of Virginia1 to use the full lane. The Code of Virginia permits bicyclists to use the full lane in a “substandard width lane,” which is defined as “a lane too narrow for a bicycle . . . and another vehicle to pass safely side by side within the lane.”

Where this condition is the reason for installing the sign, its use should be limited to roadway segments where the combined width of the right-most travel lane and any paved shoulder is 10.5’ or less, excluding the gutter pan, if any.

In order to avoid overuse of the signs that would reduce their impact and effectiveness, BIKES MAY USE FULL LANE signs should be limited to roadway segments used frequently by cyclists, or where cyclists report being intimidated by nearby motor vehicle traffic.
We are a little concerned that the signs only be used on roads 10.5' or less. Most of the roads in Fairfax are 11' or greater. This guidance seems to greatly reduce the number of locations where the signs could be used.
SHARED LANE MARKING

Following are examples of locations that may benefit from Shared Lane Markings:
  • Shared Lane Markings can provide guidance where there is a gap in or a terminus of an otherwise continuous bike lane, where constraints such as roadway width preclude the addition or extension of a bike lane.
  • Where on-street parking is permitted and frequently occupied, Shared Lane Markings can help cyclists choose an appropriate lane position, rather than riding too close to the doors of parked cars.
  • Where a roadway segment is wide enough for a bike lane in only one direction, the bike lane can be installed in the uphill direction and Shared Lane Markings can be used in the downhill direction, where cyclists are more likely to travel near the speed of motorists and may need to ride farther from the curb to have enough reaction time.
However, Shared Lane Markings shall not be used in any of the following situations:
  • As a substitute for a bike lane where conditions permit a bike lane to be marked
  • To provide wayfinding guidance to cyclists
  • To designate a roadway as a bicycle route
  • On a shared-use path or other facility where motor vehicle traffic is prohibited
  • In an exclusive turn lane, where they could communicate that cyclists are permitted to use the lane to travel straight through an intersection instead of using the appropriate through travel lane
The layout of Shared Lane Markings shall not vary from the figure depicted above.

When roadway segments with Shared Lane Markings are repaved, the segments should be evaluated to determine whether the pavement could be widened enough to mark a formal bike lane. Roadways with Shared Lane Markings should be a high priority for shoulder widening. If it is infeasible to widen the pavement, the segments should be evaluated to ensure that traffic and roadway geometric conditions continue to support the use of Shared Lane Markings.

OTHER CONSIDERATIONS

A BIKES MAY USE FULL LANE sign and a Shared Lane Marking should not normally be used on the same roadway segment, unless extreme conditions, such as a documented volume of heavy cyclist traffic and severe roadway geometry, are present to a degree that using both devices together would provide a significant additional benefit to the traveling public.

Labels: , , , , , ,

Comments:
I agree that it's unreasonable to limit BMUFL signs to locations with travel lanes narrower than 11 feet, since 11-foot to 13-foot travel lanes are clearly not safely sharable laterally between a bicyclist and any auto.

Also, Arlington County has installed both sharrows and BMUFL signs in the same location with excellent results.
 

Post a Comment

Contact FABB via email: info@fabb-bikes.org

Subscribe to the
FABB e-newsletter


Subscribe to posts:
[Atom 1.0] or [RSS 2.0]





  Bike to Work Day 2010 at Reston Town Center

  Transportation choices

This page is powered by Blogger. Isn't yours?

Archives

February 2007
March 2007
April 2007
May 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007
December 2007
January 2008
February 2008
March 2008
April 2008
May 2008
June 2008
July 2008
August 2008
September 2008
October 2008
November 2008
December 2008
January 2009
February 2009
March 2009
April 2009
May 2009
June 2009
July 2009
August 2009
September 2009
October 2009
November 2009
December 2009
January 2010
February 2010
March 2010
April 2010
May 2010
June 2010
July 2010
August 2010
September 2010
October 2010
November 2010
December 2010
January 2011
February 2011
March 2011
April 2011
May 2011
June 2011
July 2011
August 2011
September 2011
October 2011
November 2011
December 2011
January 2012
February 2012
March 2012
April 2012
May 2012
June 2012
July 2012
August 2012
September 2012
October 2012
November 2012
December 2012
January 2013
February 2013
March 2013
April 2013
May 2013
June 2013
July 2013
August 2013
September 2013
October 2013
November 2013
December 2013
January 2014
February 2014
March 2014
April 2014
May 2014
June 2014
July 2014
August 2014
September 2014
October 2014
November 2014
December 2014