The “Centre/South Streetscape and Transportation Action Plan” is proposing bike lanes in the Centre Street business district in Jamaica Plain from Eliot Street to Lakeville Rd. The images from the presentation at the January 2010 meeting of the Citizens Advisory Committee for the project show bicyclists safely out of range of car doors in the existing conditions but clearly within range when bike lanes are added (see images above, doors added to original). Shared lane markings should instead be used on Centre and South Streets to encourage bicyclists to safely use the streets and to discourage motorists from harassing bicyclists. Gore stripes can be used to indicate that the door zone is unsafe. Shared lane markings have already been used at Forest Hills and in Roslindale Square and several other locations in Boston, and are proposed for the majority of the Centre-South Street corridor that is less than 44 feet wide and thus considered too narrow for bike lanes.
Centre Street Dimensions
The drawings shown at the beginning of this article are taken from the presentation by the consultant team delivered at the January 28, 2010 meeting of the Citizens Advisory Committee. The first drawing shows the existing conditions on Centre Street between South Huntington and Monument Square. The second drawing shows how a bike lane might be inserted into the existing space without removing any parking or travel lanes or narrowing the sidewalk. Upon close examination, it becomes clear that the travel lanes in the second drawing are 15 to 16 feet wide, rather than the marked dimension of 10.5 feet. Someone merely inserted two 5-foot bike lanes without taking that space away from the travel lanes, as if the curb-to-curb width of the street could grow by 10 feet to accommodate the bike lanes. This mistake falsely suggests that more space will exist once bike lanes are installed.
The drawings have been altered by the addition of red rectangles indicating the approximate position of open doors on the parked cars. Note that in the first drawing, the bicyclists and cars shown have ample room to clear an open door. In the second drawing, the bicyclist centered in the bike lane gets hit if anyone opens a door suddenly.
The Door Zone
The bike lane would be mostly or entirely within the door zone, as can be seen in the graphic at right showing the same dimensions proposed for Centre Street. Bicycling in the door zone—within a door’s width of parked cars—is not safe. When riding faster than a walking pace, a bicyclist cannot stop in time to avoid a suddenly opened door. Although car occupants are legally responsible for making sure it is safe before opening a door, no prudent bicyclist can rely on 100% compliance with this newly adopted rule, and must ride as if a door could open at any time. “Dooring” crashes can be very serious, due to possible impacts with sharp metal and glass and a fall on to hard pavement. In the worst case, the bicyclist falls and is hit by a passing motor vehicle; documented fatalities have occurred this way while the bicyclist was riding in a presumably safe bike lane. The bicyclist must leave room for the entire bicycle to clear a door. Dana Laird was in the left part of the bike lane in Central Square, Cambridge, and her handlebar was in the door zone by only a few inches. But this was sufficient to throw her and her bicycle to the left, where a passing bus ran her over. (Other bicyclists killed by car doors opening in a bike lane include David Smith, Sixth Avenue in Manhattan, 2007, and Clinton Miceli, LaSalle St, Chicago, 2008.) Cambridge subsequently conducted a study that claimed to show that bicycle lanes keep bicyclists away from the door zone, but did not in fact show this (see Hampshire Street Study below). Like Central Square, the Centre-South business district has an elevated dooring risk because of high parking turnover.
Advantages of Shared Lane Markings
Where there is on-street parking, shared lane markings are specifically designed to position bicyclists away from the door zone (see note below). However, there are also several other advantages of shared lane markings compared to bike lanes for a corridor such as Centre-South Street:
* The same design can be used for the entire length of the corridor, even where it is a few feet narrower than the minimum that is supposed to be safe for bike lanes.
* Motorists will leave more room when overtaking bicyclists. When there is a dividing line, motorists assume it is sufficient to stay to the left of the line, whereas when overtaking in the same lane they leave as much room as possible, including using the left half of the road when necessary. (A greater average passing distance without bike lanes was documented in Evaluation of Shared-Use Facilities for Bicycles and Motor Vehicles, Transportation Research Record No. 1578, pages 111-118; William W. Hunter, John R. Feaganes, Raghavan Srinivasan, Conversions of Wide Curb Lanes: The Effect on Bicycle and Motor Vehicle Interactions. Transportation Research Record. Volume 1939 / 2005 Parkin J, Meyers C. The effect of cycle lanes on the proximity between motor traffic and cycle traffic. Accid Anal Prev. 2010 Jan;42(1):159-65. The last study concludes, “The results suggest that in the presence of a cycle lane, drivers may be driving within the confines of their own marked lane with less recognition being given to the need to provide a comfortable passing distance to cycle traffic in the adjacent cycle lane.”)
* When a bike lane is striped the remaining portion of the pre-existing travel lane becomes the “car lane,” at least in the perception of the vast majority of road users.
* Bicyclists would not be discouraged from riding in any portion of the right half of the road as necessary to pass slow or stopped vehicles, to prepare a left turn, and to avoid hazards in the road.
* Shared lane symbols will send a visible message of bicyclist legitimacy compared to the existing conditions, without sending the message that bicyclists must be in one little part of the road only. Therefore motorists would be much less likely to honk at, yell at, or assault bicyclists who dare to leave the bike lane.
* By keeping further away from the curb, bicyclists can be better seen by traffic emerging from side streets.
* Motorists will be more likely to merge as far as practicable to the right of the road in advance of making a right turn (as required by traffic law).
* Bicyclists will be less likely to overtake slow or stopped motorists on the right, in part because right-turning motorists will be further right. Because traffic moves slowly though this area, the temptation to pass on the right is high, and would be more so with a bike lane present. Overtaking on the right—except where traffic is stopped and cannot move forward—leaves bicyclists open to a collision with a car turning right, or a car on the other side of the road turning left through a gap in traffic.
Hampshire Street Study
The City of Cambridge conducted a study which claimed to show that bike lanes help to reduce dooring by moving bicyclists away from parked cars. The study showed that bicyclists did on average track 2.4 inches further left in response to a stripe being added between the car area and the bike area. However, 85% to 90% continued to ride inside the door zone. This is not surprising, since in this design, riding outside the door zone requires the cyclist to ride on the bike lane line. The study did not test lane markings showing the door-zone as a dangerous area (e.g., with gore stripes), nor did it test a shared lane symbol sufficiently away from parked cars with a line or gore markings to its right. However, the bike symbol was reduced and placed close to the left side of the lane, in an attempt to encourage bicyclists to ride their instead of the center.
Design Standards and the Door Zone
The shared lane symbol was added to the Manual on Uniform Traffic Control Devices in December 2009 and was specifically designed to take into account the width of opening doors (see drawing). The manual requires that shared lane stencils be centered a minimum of 11 feet from the curb where there is on-street parking. (Assuming a minimum shy distance of 6 inches to account for bicycle wobble, the 11 foot minimum is valid if bicycle handlebars are no wider than 24” and the widest extent of an open door is 30”. In fact cruiser bicycle handlebars can be 28” or wider, and some doors open as wide as 45”. Although most passenger cars are around 6’ wide, they can be legally parked 1’ from the curb (or illegally parked much further from the curb), and trucks can be as wide as 8.5’.)
However, bike lane standards make no explicit calculation of the minimum width needed for door clearance, except to add 1’ to the minimum 4’ bike lane width. The AASHTO and Massachusetts standards permit a parking lane next to a bike lane to be reduced from the standard 8’ to a minimum 7’, completely negating the additional foot required in the bike lane. The portion of Centre Street where a bike lane is proposed is generally 45’ but can be as narrow as 43’—so in some areas the bike lane will have to be less than 5’ wide and would be completely within the door zone.
Safety and Perceived Safety
Studies of car-bicycle crashes show that most urban car-bike collisions in daylight are the result of turning and crossing movements, not overtaking of bicyclists by motorists. However, the bicycle lane addresses only the overtaking threat, not the more common dangers. The proposed bicycle lane on Centre Street does not provide any additional width, but merely reallocates the width available. (By contrast, other projects have provided more width for bicyclists by removing travel or parking lanes.) Thus the motorist’s task in overtaking is unchanged. To the extent that bicyclists move further right, bike lanes might make things slightly easier for motorists—at the expense of more collisions with car doors. However, traffic rarely moves much faster than bicycle speed in this corridor, and most people would agree that facilitating faster traffic movement here would not improve safety. Moreover, motorists have had no problem for years squeezing to the center line, or moving partly over it, to safely pass bicyclists. It’s easier than passing double-parked cars or buses sticking out from bus stops.
Many people are deterred from bicycling because of the perception of danger from overtaking traffic. A bike lane mostly in the door zone caters to this fear while increasing real dangers. A shared lane marking, by contrast, provides the legitimacy that bicyclists crave without promoting dangerous behaviors. Some people are so afraid of traffic that no amount of paint on the roadway will induce them to bicycle in the city. It is possible for these people to gradually overcome these fears with the guidance from more experienced bicyclists who show them what they most need to be concerned about to avoid injury. Learning to avoid the practices that “everyone knows” are safer, such as hugging the edge of the road and riding on the sidewalk or facing on-coming traffic is what reduces bicyclist injuries. While road design cannot teach bicyclists how to ride safely, it should not encourage them to ride dangerously.