Archive for Planning and Engineering

Hillsborough Street’s Door Zone Bike Lanes

The City of Raleigh recently striped bike lanes within the door zone of on-street parking on Hillsborough Street, and is asking for feedback on the design. Cycling safety educators teach that cyclists should ride well outside of the door zone, which on Hillsborough Street means outside of the bike lane. The following is the feedback I provided.

 

Dear Raleigh Bicycle and Pedestrian Advisory Commission,

I am writing to urge the City of Raleigh to remove the bike lane designation from the door zone area of Hillsborough Street in favor of either no markings or a shared lane marking in the center of the effective travel lane. My recommendation is based on 20 years of experience cycling on Hillsborough Street as a utility cyclist before and after its redesign, over a decade of research into bicyclist safety, crash data, engineering[1], and operating practices, and my training and experience as a League Certified Instructor through the League of American Bicyclists[2].

The design of the striped bicycle lane on Hillsborough Street is unreasonably hazardous because it encourages bicyclists to operate in an area that (1) places them within impact range of opening doors with a high rate of parking turnover, (2) invites motorists to squeeze by at usafe close distance, and (3) encourages cyclists to pass congested motor traffic on the right, in drivers’ blind spots, on a corridor where drivers often move to the right without warning.

Below is a colorized photo of the current bike lane where the door of a parked minivan has been opened, blocking almost the entire width of the bike lane. Note that the tires of the minivan are touching the curb. Since a door may open without warning at zero sight distance, a cyclist who operates within the red area of the bike lane is in danger of serious injury by the door itself, or by being thrown left into traffic when the door strikes the right side of the handlebars. If the cyclist rides farther left, in the yellow area that is either on the bike lane stripe or just outside the bike lane, car drivers will pass at unsafe close distance, and bus drivers cannot pass at more than a few inches of clearance – not only illegal, but very likely to cause a collision.

The diagram below[3] illustrates just how close to the door zone a transit bus will be if its driver attempts to pass a cyclist on Hillsborough Street. The vehicle and lane widths are drawn to scale for the existing conditions: an 11’ travel lane, 5’ bike lane, parked vehicle side at the edge of the bike lane.  Since the left side of the travel lane is a raised median, the bus driver must allow for at least a foot of shy distance on the left. There is no room for a cyclist to travel safely between an opened door and a passing bus.

 

Cycling safety experts and instructors teach cyclists to stay at least five feet away from the sides of parked cars in order to avoid being startled into swerving left into the path of overtaking traffic when a door opens suddenly.  Motorists will never look for or see bicyclists reliably enough for it to be acceptably safe for cyclists to operate in the door zone.  For a detailed explanation of the required distance, I strongly recommend the following short video featuring League of American Bicyclists Education Director Preston Tyree: http://www.youtube.com/watch?v=1TQ7aID1jHs

Avoiding the door zone on Hillsborough Street requires cyclists to use the general purpose travel lane.  However, since the general purpose travel lane is too narrow for most vehicles to operate side-by-side with bicyclists safely, it is strongly recommended that cyclists ride near the center of the general purpose travel lane to deter unsafe close passing.  This is a basic principle taught in defensive bicycle driving classes.  On a low speed urban street with a high rate of parking turnover, high volume of bus traffic, and numerous intersections, cycling lawfully in the center of the general purpose travel lane is far safer than traveling in the door zone.

In order to remind motorists that bicyclists are entitled to operate in line with traffic in the general purpose travel lane and encourage bicyclists to ride outside of the door zone, shared lane markings, AKA sharrows, may be placed in the center of the travel lane, as shown below[4].  This has been done on urban streets in many cities to encourage safer cycling and reduce the potential for motorist harassment of lawfully operating cyclists.

 

The center of the travel lane is a comfortable place to bike on Hillsborough Street.  When classes are in session, vehicle congestion, pedestrian traffic, and parking turnover reduces average motor vehicle speeds there to speeds easily maintained by bicycle, and peak speeds are usually limited to under 20 miles per hour, with 15 mph max typical at rush hour. When I ride a bike on the new Hillsborough section (in the general purpose travel lane) I find that my cycling speed is normally limited by the traffic in front of me and that I do not delay motorists behind me any more than if I were using my car.  However, now that the door zone bike lane is striped, I often see cyclists attempting to pass traffic on the right, in the narrow space between the parked cars and cars, trucks, and buses in the travel lane.  These cyclists are often forced to slow or stop for right-turning motorists, parking motorists, opening car doors, stopping buses, and pedestrians standing in the door zone.  By comparison, by using the general purpose travel lane, a cyclist can avoid the conflict zone entirely, and can pass parking drivers and right-turning drivers safely on the left.

When classes are not in session, traffic is relatively light.  Peak vehicle speeds on this section of Hillsborough may rise to near 25 mph, which is still not a danger to lawfully operating cyclists in the center of the lane.  Cyclists can often still keep up with traffic on the flat and downhill sections, but may feel social pressure to defer to motorists on the uphill sections.  A shared lane marking in the center of the lane may help deter motorist harassment in this case, and if the cyclist wants to allow traffic to pass, he or she can wait until there is a safe place to pull over, such as where there is no parking in use.

Many communities across the US are turning to shared lane markings to encourage safer cycling outside of door zones and in line with slow urban traffic (see photos at the end of this note).  I urge Raleighto follow this trend and remove the hazard that has been created on Hillsborough Street.  I believe it is unethical to encourage novice cyclists to ride in the door zone by striping it as a bike lane. The door zone bike lane design is completely contrary to the defensive bicycling methods that cycling safety instructors have been teaching for decades.  Lastly, the resulting increase in motorist harassment of knowledgeable cyclists who stay out of the door zone bike lane has made Hillsborough Street a much less pleasant place to travel by bike.

Sincerely,

Steven Goodridge

LCI # 1690

Ph.D. Electrical Engineering NCSU 1997

MS Electrical Engineering NCSU 1994



[1] Note that I am not a traffic engineer and am not a PE, although I do hold engineering degrees.

[2] Note that my comments are not intended to represent the League of American Bicyclists.

[3] Thanks to LCI Dan Gutierrez for providing this diagram.

[4] Thanks to LCI Dan Gutierrez for providing this diagram.

 

Shared lane marking in the center of the lane on St. Mary's Street, Raleigh