Bicyclist narrowly avoids opening door -- Centre St, Jamaica Plain, Mass.

This bicyclist had to swerve as the oblivious motorist flung open her door on Centre Street in the heart of the business district where parking turnover is high and traffic is slow.

This Thursday the City of Boston will present its proposal for bike markings on South Street and Centre St from Forest Hills to Jackson Square in Jamaica Plain. The proposal will be:

* door-zone bike lanes (DZBLs) from The Monument to Lakeview St, except for a two-block section where the width dips below 44 feet, where shared lane markings (SLMs) are proposed;

* DZBLs on the uphill side only, and on the downhill side a narrow lane with an SLM in the middle, from Hyde Square to Jackson Square and from Sedgwick Street to Jamaica Street.

* SLMs elsewhere.

The parking lane be striped at 7 feet from the curb throughout the corridor. Some additional marking to indicate the door zone may be discussed.

Most people agree that riding in the door zone is not a good idea (except when deliberately going very slowly). But some DZBL proponents argue that a) DZBLs actually move people away from parked cars, and b) you won’t get people to ride outside of the door zone.

To use their own words:

a) “First, [the additional distance between bicyclists and parked cars found in the Hampshire St. Study is] 2.4 inches further away, not 2, and that’s merely the median (average) distance   It’s clearly in the author’s conclusion that a narrowing of the spread of distances was the significant finding. Namely, that far fewer people were riding very close to the doors. And when we talk about doors and the door zone, keep in mind that when you’re on the street and a door opens, inches definitely count.”  (Pete Stidman)

b) “The problem that you are trying to solve is how to get bicyclists to ride completely outside the door zone. Without removing parking or somehow changing the dimensions of the roadway, I don’t think any type of facility and/or education will be effective in doing so.” (Charlie Denison)

I have some responses to both points:

a) The Hampshire Street study in Cambridge found that bicyclists moved away from the curb after marking a solid line at 12 feet from the curb — but they moved by an average of less than 3 inches. A San Francisco study found that shared lane markings moved bicyclists away from the door zone by an average of 8 inches. The lead author of the Hampshire Street Study has agreed with my assessment that a wheel track 11 feet from the curb, not 10 feet, is the proper cut-off for being outside the door zone 85% of the time with a 6″ margin to spare. Only 11% of bicyclists in the study were riding this far away. I am currently doing some re-analysis of the study data. One reason that few were out of the door zone is that they did the survey at rush hour, mostly approaching intersections. Traffic on Hampshire Street regularly queues up for several blocks approaching red signals in the peak period. So some of the bicyclists in the door zone may have been slowly passing cars on the right instead of being stuck in traffic for several light cycles.

b) Boston has added Shared Lane Markings in the middle of the lane in several places, and proposes to do so in the Centre-South corridor–where there is only one travel lane in each direction. These markings are supposed to direct bicyclists to ride in the middle of the lane. If it is possible to encourage people to ride in the middle of the lane, surely it is possible to encourage them to ride outside the door zone where they will impede traffic much less (at those times where traffic is moving faster than bicycle speed). A bicyclist who rides with his or her wheel at 11 feet from the curb is safely out of the door zone and in most places in the corridor is leaving 10 or more feet for a 6-foot wide passenger car to pass without changing lanes. (In fact, most drivers will crowd or cross the center line in order to provide the bicyclist with plenty of extra room when passing.)

I propose a solid white line at 10 feet from the curb with a shared lane marking completely to its left. This will provide clear guidance that bicyclists are expected to stay out of the door zone. Another San Francisco study showed that using a 9 foot parking lane instead of a 7-foot one moves the average spacing of parked cars about 4 inches further from the curb. I don’t think this a significant concern. If it is, then a solid white line could be marked at 7 feet from the curb with a series of diagonal lines (gore stripes) between the lines at 10 and 7 feet — to indicate the buffer zone to be avoided. This design would be used consistently throughout the corridor, instead of the confusing alternation between DZBL and SLM that is proposed.

To my knowledge, no city has yet tried a SLM to the left of a line indicating the door zone (as distinct from a BL with the symbol to the right of the line, or an SLM with no line).  There is an opportunity to find out how effective this configuration is in pulling people away from doors. In any case we know that SLMs, even without a line, can be more effect than DZBLs in pulling bicyclists away from the door zone.

Please come to the meeting to support shared lane markings instead of door zone bike lanes. Defend the right of bicyclists to use as much of the road as needed for safety and travel. Don’t lure bicyclists into the danger zone. The details:

Thursday, April 29^th

Agassiz School cafeteria
20 Child Street, Jamaica Plain, Mass.
6 pm to 8 pm

“Bike accommodations” will be the first and major topic of the meeting.

That little stripe is not going to protect you,” Schimek said, explaining he is worried the bike lane message will be, “‘You novice cyclists, come out here. You see that bike lane, and you’re safe because that’s what a bike lane is for.

I believe I was trying to say that that the bike lane tells new bicyclists that they will be safe riding in it, even though in the proposed design they will be smack in the danger (door) zone. And this summary also got mangled:

Bike lanes suggest that bicyclists have to use them, when in fact they do not, Schimek said. That confusion can lead to more car-bike conflicts, and some research shows it leads drivers to come closer to bikes in the lane, he said. Bike lanes also lock riders onto the right-hand side of the street, when they should be on the left to make left-hand turns safely, he noted.

What I was saying is that most people act as if there is a legal requirement to use bike lanes, even if there is not. It is the bike lane stripes that can cause more conflicts, by encouraging motorists to keep left when turning right, encouraging bicyclists to pass on the right, and even suggesting that bicyclists should turn left from the bike lane. And then there’s this one:

An illusion is exactly what 5-foot bike lanes on Centre Street would be, Schimek said. He blasted the idea that bike lanes are good because they make potential riders feel safer as a “backhanded…indirect and disingenuous argument.”

The argument that I “blasted” is the one repeated in the article: even if door-zone bike lanes are more dangerous, having more bicyclists on the road will make all bicyclists safer.

Another mangled point:

Schimek noted that the city’s own design illustration for Centre Street bike lanes showed people riding down the middle of the lanes. In fact, riders are supposed to ride along the left-hand line in a bike lane to avoid dooring. Without education, new riders attracted to the bike lanes are set up for disaster, he said. And even if there is education, the lanes may be so narrow that riders are in the dooring zone anyway, he said.

Ruch had a copy of the illustration showing bicyclists in the door zone with bike lanes and outside the door zone without (see previous post). He did not communicate that point. Riders are not “supposed to ride along the left-hand line in a bike lane,” they are supposed to ride in the middle of the bike lane, following normal lane use expectations — and several studies show this is what they actually do. I don’t use the meaningless term (in this context) “education,” I prefer to talk about learning from experience (i.e., being doored, or narrowly avoiding a door), and training (from friends, books, or formal classes). The final point is that riding outside the door zone will probably put the bicyclist at least partly outside the bike lane. And thus we end up with the paradox that the only safe way to use these bike lanes is not to use them.

Ruch also makes this blooper:

The dispute is over methods—especially whether it makes sense to slightly reduce the width of car lanes on Centre and add 5-foot bike lanes.

Where are those “car lanes” on Centre Street? All I see — and all the law sees — is a road shared by cars, trucks, buses, motorcycles, and, yes, bicycles.

News about the famous Hampshire Street Bike Lane study coming soon.

Concord Avenue 'Raised Bicycle Lanes' - Not Part of "Roadway"

Concord Avenue north of Fresh Pond in Cambridge has perfectly nice, five-foot bike lanes. They’re not even in the door zone, since there is no on-street parking. But Cambridge is planning to take them away, narrow the roadway, and force bicyclists to ride on the sidewalk. The bike lanes were striped 10 years ago as part of a successful “road diet” project. John Allen has posted a history and more information about the proposed project. The current project, whose limits are Fresh Pond Parkway and Blanchard Road, includes water main installation and started this week.  The planned “raised bike lanes” are at sidewalk level and in most places will be separated from the travel lanes by a 6-inch high curb. A bicyclist who strays too close to the edge of the “bike lane” risks falling into the travel lane. In other words, the new “bicycle lanes” are really “sidewalks”. A sidewalk by any other name is still a dangerous place to ride a bike at anything faster than walking speed. Look at the above excerpt from the construction drawings. They show clearly that the “roadway” includes the “travel lane” but not the ”bicycle lane.”  This turns out to be an important detail.

MassDOT’s Engineering Directive on Bicycle Accommodation says that “Bicycle accommodation shall be in accordance with Chapter 5 of the [Project Development & Design] Guide and the 1999 AASHTO Guide for the Development of Bicycle Facilities.” What do those documents say? Chapter 5 of the Project Development & Design Guide says: ”Bicycle lanes are portions of the traveled way designed for bicycle use. .  .  . Bicycle lanes should be designated by a 6-inch solid white line on the right edge of the motor vehicle travel lane [sic].” (section 5.3.2.1).

The 1999 AASHTO Guide for the Development of Bicycle Facilities is more precise. It has the following definitions: “BICYCLE LANE or BIKE LANE—A portion of a roadway which has been designated by striping, signing and pavement markings for the preferential or exclusive use of bicyclists. ROADWAY—The portion of the highway, including shoulders, intended for vehicular use.” It further says that “A bike lane should be delineated from the motor vehicle travel lanes with a 150-mm (6-inch) solid white line.”

In other words, the official design manuals say that bike lanes are part of the roadway, not the sidewalk, and are separated from other lanes by lines, not curbs. The AASHTO bike guide also includes this helpful guidance: “Sidewalks generally are not acceptable for bicycling. However, in a few limited situations, such as on long and narrow bridges and where bicyclists are incidental or infrequent users, the sidewalk can serve as an alternate facility, provided any significant difference in height from the roadway is protected by a suitable barrier between the sidewalk and roadway.” The Concord Ave project clearly does not meet the requirements for exceptional designation of a sidewalk as a bike facility, and even if it did, the design guidelines require a barrier to prevent bicyclists from falling into the roadway — an important detail that Cambridge has not followed in this project.

Well, what if Cambridge just edits the drawings so that they say “bicycle path” instead of “bicycle lane”? One problem is that there is no design standard for a bicycle facility on the sidewalk that prohibits pedestrians; the only standards are for “shared use paths” — shared by pedestrians and bicyclists. Moreover, the Project Development & Design Guide says this: “Shared use paths are facilities on exclusive right-of-way with minimal cross flow by motor vehicles. Shared use paths should be thought of as a complementary system of off-road transportation routes for bicyclists and others that serves as a necessary extension to the roadway network. The presence of a shared use path near a roadway does not eliminate the need to accommodate bicyclists within a roadway” (Section 5.3.2.4). If Cambridge were to call the “raised bicycle lane” a “path” it would not be able to narrow the travel lanes to only 12 feet, as proposed, but would have to leave at least another 3 foot shoulder to provide the minimum 15 feet of room for motorists to comfortably pass bicyclists according to MassDOT’s Engineering Directive previously mentioned.

Ok, but does Cambridge really have to follow these design guidelines? To pay for this project Cambridge applied for and apparently received a grant from the Public Works Economic Development (PWED) Program, formerly administered by the Executive Office of Transportation, now part of MassDOT. So it would seem that MassDOT’s own Engineering Directive should apply.

If not, there is a higher authority. All traffic control devices in the U.S. must conform with the Manual on Uniform Traffic Control Devices published by the Federal Highway Administration. The manual has the following definitions:
“Bicycle Lane—a portion of a roadway that has been designated for preferential or exclusive use by bicyclists by pavement markings and, if used, signs.
Roadway—that portion of a highway improved, designed, or ordinarily used for vehicular travel and parking lanes, but exclusive of the sidewalk, berm, or shoulder even though such sidewalk, berm, or shoulder is used by persons riding bicycles or other human-powered vehicles.”
In other words, a Bicycle Lane that is not part of a roadway does not comply with the manual.
Noncompliance with engineering directives and design manuals could mean that Cambridge would be held liable by a court in the event of a lawsuit by an injured bicyclist.

The Livable Streets Alliance endorsed the project, saying, “The Concord Avenue reconstruction plan pushes for best practice for street design. It includes well-designed and inviting facilities for pedestrians, bicyclists, and motorists alike. Of particular note, there is a raised bicycle lane (cycle track) included as part of the project, a type of facility that has been gaining interest among the public, but which we currently have very few of.” WalkBoston endorsed it as well.

Seen in Berkeley, Calif, Ride on the Street, Walk on the Sidewalk

I remember seeing these signs in Berkeley some years ago. They are in complete violation of the MUTCD (wrong color, symbols, and font), but they do convey a useful message, particularly by citing the relevant city and state codes. I think (an improved version of) these signs would nicely complement Shared Lane Markings that I have suggested as an alternative to door-zone bike lanes in the Jamaica Plain business district. Perhaps a combined sign would do the trick, with an arrow pointing left under the Ride on the Street message and another arrow pointing right for the Not on the Sidewalk message.

Someone is sure to raise the “sign pollution” issue. Well, I can point to dozens of signs that could be removed from the corridor. I counted 10 “SLOW”" signs (or, less grammatically, “DRIVE SLOW”), and perhaps a few more have sprouted since then. These signs violate the basic principle of the MUTCD that signs should convey a clear meaning. How fast is SLOW? Only a little bit above the statutory 30 mph speed limit? Ironically there are no speed limit signs in the whole Centre-South corridor.

An even larger source of sign pollution are pedestrian crossing warning signs. They are haphazardly posted a block or two before a crosswalk and (rarely) near the crosswalk. Usually they are too high to be noticed. Boston has recently used these warning signs in a much more effective way: at the crosswalk, mounted as low as possible, with an arrow pointing to the crosswalk.  This helps alert drivers of the need to yield and reinforces the crosswalk pavement markings when they can be difficult to see (at night and after the thermoplastic begins to wear).

Tracks along Roadway Warning from Portland

The tragic loss of a young bicyclist this week reminds me of another warning sign that we really do need: to alert cyclists about the dangers of trolley tracks. This sign is used in Portland, Oregon, but nowhere else that I know of. It is not in the MUTCD. Fortunately, we no longer need them in the Centre-South corridor (since the tracks were paved over after being an unused hazard for 23 years), but we do need them in the remaining places that trolley tracks are in the road (not in a reservation): along the E branch from Heath St to Brigham Circle, and in Cleveland Circle.

Jackson Square Bike Lane Concept

A proposal for bike lanes on Centre Street between Lamartine St and Sunnyside St (near Jackson Square) was floated at the March 23 meeting of the Centre South Transportation Action Plan Citizens’ Advisory Committee. The 42-ft curb-to-curb width is just a bit too narrow for the bare minimum bike lanes proposed for Centre Street between Elliot St and Lakeview St. The necessary width would be obtained by eliminating parking on one side of the street only. (See the presentation, pages 56 – 61.) Currently there is about 21 ft (travel lane + parking lane) on each side of the street. The suggested new configuration is an 11 ft travel lane and 4 ft parking lane on one side and an 11 ft travel lane with a 5 ft bike lane, 8 ft parking lane on the other side. The remaining 3 ft would be used to widen the existing 8 ft sidewalk on one side. The proposal would leave on-street parking in front of most businesses that do not have on-street parking. This would be accomplished by switching the side without parking from the south side near Mozart Park to the north side near Bromley-Heath. Nevertheless, at least 37 on-street spaces would have to go.

The proposal would remove the door-zone threat on the side of the street where parking is newly prohibited. And the remaining parking lane + bike lane on the other side would be 13 ft wide instead of the 12 ft proposed for central Jamaica Plain, meaning that 1 to 2 ft of the nominally 5 ft bike lane would be safe for riding, rather than 0 to 1 ft. A slightly wider sidewalk would be nice, although the 3 ft could be used instead as a marked buffer area so the bike lane could be out of the door zone (more on that concept in a later post).

Two alternate proposals would use the space from eliminating a parking lane to widen the sidewalks, and would also narrow the travel lanes to 11 ft (with no bike lanes). In other words, safe cyclists would frequently have to ride in the middle of the lane, because there would be insufficient room for motorists to pass safely, particularly on the side next to on-street parking. These alternate proposals are clearly a dis-improvement from the point of view of bicycling.

But will it be possible to remove any parking? Michael Halle, a member of the CAC, is quoted in the JP Gazette. “Halle noted that the area is right next to a T station and a huge parking lot at Stop & Shop that he described as ‘underused.’  .  .   .  He said if on-street parking can’t be cut here in favor of bikes or pedestrians, ‘it can’t be done anywhere.’”

I know of three places in the Boston area where on-street parking has been removed, in part to improve bicycling conditions:

* Huntington Avenue between Opera Place and Longwood Avenue (adjacent to Northeastern, MassArt, the MFA, and Wentworth).

* Mass Ave, Cambridge, adjacent to MIT.

* North Harvard St, Allston, adjacent to the Harvard Business School (just last year).

(I can’t think of any other examples in Cambridge–anybody else know of any?) What do all of these examples have in common? Parking was removed immediately adjacent to institutions only, not where there were businesses or residents abutting the street. All these institutions have large off-street parking facilities. While the Jackson Square proposal attempts to avoid businesses, it is not really analogous to the three successful removals. We will see if this proposal is implemented.

Meanwhile, one important consideration for bicyclists in this area is that there is a significant downhill grade from Stop and Shop to Lamartine Street. Perhaps parking can be removed just in front of Bromley-Heath, on the uphill side, where bicyclists go slowly. If not, the centerline could be moved two feet so that the downhill side would have a narrow (11 ft) travel lane, which could be outfitted with a Shared Lane Marking in its middle, and the uphill side could have a wide (15′) travel lane (and an optional Shared Lane Marking 12 ft from the curb).  (A door-zone bike lane could be used instead on that side only, although this is not preferable to a shared lane, for reasons I’ve previously described.)

Meanwhile, we’re hoping that the (separate) Jackson Square project will fix the basic problem that the drop-off area needs to be adjacent to the station, not on the other side of the street. Who was the genius who designed that? It’s created delay and danger for probably 23 years now.

Centre Street with and without bike lanes -- the street grew by 10 ft!

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.

Door Zone Buffer Gore Stripes (Paris)

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

Correct Riding Position is Outside of Bike Lane (on Lane Line)

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

Shared Lane Marking in Roslindale Square

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

Shared lane marking considers 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.