Bike Boxes

The National Association of City Transportation Officials defines “bike boxes” as follows:

A bike box is a designated area at the head of a traffic lane at a signalized intersection that provides bicyclists with a safe and visible way to get ahead of queuing traffic during the red signal phase.

http://nacto.org/cities-for-cycling/design-guide/intersection-treatments/bike-box/

A typical installation is shown below. Bicyclists pass queued motor traffic on the right and can then move left into the bike box to wait ahead of motor vehicles before going straight or turning left.

Typical bike box installation in Oregon

Bike boxes are not approved traffic control markings in the Manual on Uniform Traffic Control Devices (MUTCD) and are not included in the American Association of State Highway and Transportation Official (AASHTO) Guide to the Development of Bicycle Facilities.

Bike boxes suffer from two fundamental design flaws:

  1. They direct bicyclists to pass on the right side of traffic that may turn right at any moment.
  2. They direct bicyclists to turn left and cross in front of other traffic with no signal-protected clearance interval at near zero sight distance.

Right Hook Hazard

A marked curbside bike lane directs straight-traveling bicyclists to pass to the right side of motor traffic that may turn right, in violation of the normal destination-positioning traffic rule. A motor vehicle driver in the general purpose lane can turn right with no advance warning to the bicyclist during a red signal or when the signal turns green. If the motor vehicle is a truck or bus, the rear wheels will track to the inside of the turn and crush the bicyclist. This is an increasingly common cause of fatalities to bicyclists in urban areas.  The right-turning driver’s attention is focused on traffic coming from the left and on traffic ahead of his path, and not on unexpected traffic overtaking in his blind spot.

Right Hook

Right hook hazard in curbside bike lane

 

There is no time when it is safe for a bicyclist to overtake to the right of a vehicle at the stop line.  To avoid this hazard, bicyclists and motor vehicle drivers who might turn right should merge in line with one another and sort themselves by destination before reaching the intersection. Many bicycling safety experts recommend ending bike lane markings well in advance of an intersection to facilitate this.  This is why California’s roadway design standard requires the bike lane stripe be either dropped or dashed within 100-200 feet of the intersection, and the California Vehicle Code requires motorists to merge to the curb – into the bike lane – when approaching a right turn.

Left Turn Signal Change Hazard

The bike box provides a waiting area for left-turning bicyclists ahead of queued motor traffic. By design, the bike box directs bicyclists to move into this waiting area from the bike lane “during the red signal phase.” If the signal turns green while the left-turning bicyclist attempts to move left into the waiting area, motor traffic may start moving with no warning to the cyclist, and motor vehicle operators responding to the green signal may not notice the bicyclist crossing suddenly in front of them.  This is especially hazardous in multiple-lane installations where traffic in one lane blocks view of the crossing bicyclist from the driver in the next lane.

Signal Change Hazard

Signal change hazard for bike box user

If the left-turning bicyclist is still in the bike lane when the signal turns green, the bicyclist must wait in the bike lane for a red signal or a large gap in traffic before they can move into the left turn position. By stopping in the bike lane during a green light, the left-turning bicyclist creates a potential conflict for other bicyclists who wish to travel straight or turn right.

Normal Execution of Left Turns

The safest way for a bicyclist to perform a left turn in urban traffic is to merge into the appropriate left turn position in advance while approaching the intersection like any other driver. This is done by looking for a traffic gap which, if not already present, can be created by signaling one’s intentions to other drivers. If the first driver does not provide space for merging, the following driver most likely will, or failing that, the next driver. The cyclist must begin the merge operation early enough to find an adequate gap or cooperative driver before reaching the intersection or stopped queue. This is a basic bicycle driving skill that can be easily mastered by anyone capable of learning to drive a car. However, on some roads with multiple through of lanes of high-volume high-speed traffic, some cyclists may feel uncomfortable or intimidated doing this, which may lead transportation planners to consider other possibilities.

Pedestrian-Style Left Turns

A pedestrian-style left turn is executed by the bicyclist by traveling straight across the intersection, stopping at the corner, turning 90 degrees in place, and continuing across the second leg of the intersection when the next green appears for that direction. The bicyclist may use the roadway or the crosswalk depending on the intersection design and local laws. The main disadvantages of this method are greater delay than a normal left turn, and potential conflicts with right turning traffic.

Pedestrian Left Turn

Pedestrian-style left turn

Cross-Street Bike Box

A cross-street bike box facilitates a variation on the pedestrian-style left turn where instead of traveling all the way to the opposite corner on the first leg, the bicyclist stops in a reserved space between the crosswalk and advanced stop line for the through lane traveling across the second leg. This keeps the cyclist out of the path of right-hook conflicts for the second leg of the crossing.  Because the bicyclist entering the cross-street bike box does not overtake on the right side of traffic and is provided clear signal protection with clearance interval, the bicyclist can enter the cross street bike box safely.

Cross-Street Bike Box

Cross street bike box for alternative pedestrian-style left turn

Separate Signal Phases for Bikeways

The only reasonably safe way to protect bicyclists turning left or traveling straight through an intersection from a position to the right of traffic with a conflicting destination is to provide separate signal phases for the bikeway and the general purpose lanes with right-turn-on-red prohibited. This has been done on many bikeways in Europe, and in some places in the US, such as the intersection of Broadway and Williams in Portland, Oregon.  The disadvantage of using separate signal phases is that this reduces the green time available for motorists and bicyclists and consequently increases delay for both user groups. The increased delay for bicyclists also results in lower rates of bicyclist compliance. For these reasons, separate signal phases for bicyclists are rarely used in the United States.

[UPDATE]: See this Portland Mercury news story about increased crash rates reported by the city of Portland at intersections where bike boxes were installed: City Finds Bike Boxes May Actually Increase Crashes

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

NC Bike Ed

Check out the new NC Bike Ed blog, which features educational information for cyclists, police, transportation engineers, and planners.

Of particular interest is news about the “Bicyclist Safety and Law Enforcement” training program that has been going out to police departments in the Triangle this year.  A condensed version of the presentation can be viewed on the site.

Mission

Bicyclists are drivers of vehicles.

Every street is a bicycle facility.

Bicyclists have the right to access every destination reachable by public roads, and this right is protected by the traffic laws of every state.  North Carolina law specifically defines bicycles as vehicles and assigns bicycle operators all of the rights and duties of drivers of vehicles on roads.  Scientific analysis of bicycling practice in the United States shows that bicyclists who behave as drivers of street vehicles and follow the Rules of the Road enjoy travel that is much safer and much more convenient than those who do not.

Unfortunately, common attitudes about bicycle operation are based on taboo and prejudice rather than science and law.  As a result, people on bicycles have often been treated as inferior road users and systematically discouraged from traveling on important roads to important destinations.  The effectiveness of lawful bicycle driving for traffic negotiation has been ignored by much of the public.  Even worse, many bicyclists have been encouraged by popular culture to operate in a dangerous manner when in traffic.  The North Carolina Coalition for Bicycle Driving is a grass-roots organization of cyclists who are dedicated to advancing public understanding of the principles of vehicular-style bicycle driving, and incorporating these principles into public policy.

Bicycle drivers advocate:
 

1.  Bicycle driver education based on scientific traffic negotiation principles and the Rules of the Road as they apply to drivers of vehicles.

2.  Universal access for cyclists to every destination reachable by public roads.

3.  Accommodation of cyclists in travel lanes as equal drivers of vehicles, without segregation, except where there is scientifically valid evidence of safety and operational advantages significant enough to outweigh the disadvantages. Wide (14? or more) outside lanes are the preferred design for those roads where it is desirable to facilitate the convenient passing of cyclists by motorists without motorists changing lanes.

4.  Design and adjustment of traffic signal sensors to detect bicycles

5.  Enforcement of non-discriminatory traffic laws that reduce or prevent collisions.

Adding width to a road provides a more convenient passing facility, not a bicycle facility. The bicycle facility is already there.