Bike Lanes for Jamaica Plain?

<b>Centre Street with and without Bike Lane -- the Street has Grown Wider!</b>
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 Zone (Paris)
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)
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

<b>Shared Lane Marking in Roslindale Square</b>
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

<b>Shared lane marking considers the door zone</b>
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.


  1. While I agree that when bike lanes that are striped with the dimensions proposed that a large part of the bike lane is in the door zone, I don’t think sharrows are necessarily better or solve the problem.

    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.

    While sharrows do guide bicyclists to the absolute safest riding location, most bicyclists I’ve observed do not ride over the center of the sharrow. Especially when there are many vehicles passing them, they tend to ride to the right of the center of the sharrow, particularly when there is not enough width for a motor vehicle to pass relatively easily.

    As I observe bicyclists in bike lanes, most are pretty keen at when to ride very close to the left edge (when they are moving quickly, in high parking-turnover areas or next to cab stands, etc) and when to ride more towards the center of the lane (in areas with less parking turnover or lighter traffic volumes).

    Most bicyclists are well aware of the dooring risk, but with both bike lanes and sharrows, it seems like most tend to make a judgement at any given time of where to position themselves based on their speed, parking turnover, and passing traffic, in combination with the striping on the road.

    In addition, bike lanes of the proposed dimensions have been widely used in the Boston area and nationwide, and to the best of my knowledge, I am not aware of an increase of dooring incidents. If this were indeed the case, I would be concerned, and I would hope we could find a way to stripe a better bike lane.

    Furthermore, when bicyclists are surveyed as to what types of facilities they prefer, bike lanes are at the top of the list, above sharrows. (I believe Boston’s bicyclist survey from 2009 shows this as well.) If bike lanes were truly hazardous because of the dooring risk, bicyclists wouldn’t be asking for them.

    I would definitely be interested to see a study that shows that sharrows are more effective than bike lanes at getting bicyclists to ride further from parked cars. My own experience shows the opposite, as the Cambridge study shows as well.

    So while I do agree that the dooring risk is a problem, I don’t think it’s a big enough problem such that bike lanes cannot still be an effective facility in the dimensions proposed for JP.

  2. Charlie —
    I agree that directing bicyclists away from the door zone is a problem even with shared lane markings. That’s why I suggested “gore stripes” near the door zone (as shown in the Paris picture I added). The Hampshire St study didn’t test this, nor did they test putting a bike symbol to the *left* of a line indicating the door zone. All they showed is that adding a stripe between travel and parking lanes moved bicyclists on average 2 inches to the left– but not far enough left to be outside of the door zone (which would require riding on the line or further left).

    Anecdotally, it seems that some people learn to stay out of the door zone after one or two ‘doorings’. Better still, those who take a bike class learn without getting hurt (or from friends, or from reading). I don’t accept your fatalistic assessment that neither roadway design nor education can keep people out of the door zone.

    You say that “Most bicyclists are well aware of the dooring risk” but that they will only move out of the door zone sometimes (high turnover) or not completely out if that means being in the travel lane. It’s easy to fail to appreciate the risk of a door opening, especially since everyone has been taught to fear moving traffic from behind, not opening doors. Do most people know that Dana Laird got only the tip of her handlebars caught by a door — and died? I think not.

    You downplay the risk (”I don’t think it’s a big enough problem such that bike lanes cannot still be an effective facility in the dimensions proposed for JP”). But there are real problems with door zone bike lanes:
    1. Although many (novice) bicyclists shy to the right without a bike lane, thinking they are keeping farther from danger rather than closer to it, the bike lane reinforces and sanctions this belief.
    2. With a door zone bike lane, “educating” the bicyclist to be far enough away requires overcoming both common but erroneous knowledge and also the government stamp of approval on the roadway.
    3. The bicyclist who accepts the truth that he or she is much more likely to get injured from a parked car than from a moving one must confront the potential wrath of motorists when not riding completely in the bike lane (to avoid doors) or when leaving it altogether (for many other reasons).

    The shared lane marking gives the government stamp of approval to bicycling without giving over most of the road (and the most usable part) to motorists. Yes, I know that many people believe that roads are for cars not bikes, but that’s not what the law says.

    We’re only talking about 9 short blocks here. For all the rest of the corridor from Forest Hills to Jackson Square, only shared lane markings are under consideration. Ironically, these 9 blocks have the slowest traffic (bicyclists go faster than motorists) and the highest parking turnover (most opening doors).

    I must question the logic in this statement: “If bike lanes were truly hazardous because of the dooring risk, bicyclists wouldn’t be asking for them.” This would be true only if it were impossible for bicyclists to ask for facilities that are hazardous.

    Sure, everyone would like a wider bike lane further out from parked cars. But that’s not an option anyone is offering (I doubt on-street parking will be gone any time soon). Forced to choose between a bike lane that reinforces dangerous practices and none at all, many advocates opt for the former. I don’t think this is an ethical choice, unless one personally is willing to habitually ride in the door zone at a speed above 8 mph. If you won’t do it yourself, why encourage others to? To say that they would do it anyhow is not an excuse. When you create a bike lane you create an expectation that bicyclists will ride *in* it (an expectation often enforced outside the law by vigilantes and even police officers). When the dimensions are so tight that the only safe place to ride is halfway outside the bike lane, you are creating a contradiction. (”We’ve installed bike lanes here to make you safer — now learn to ride half way outside of them.”)

    Then there are those bicyclists who agree that door zone bike lanes are dangerous, and believe that the only safe solution is a cycle track between parked cars and the curb . . .

  3. How big a problem is dooring? In a word, huge.
    The problem is seldom measured, because of a loophole. Statistics are gathered on collisions between bicyclists and moving motor vehicles. But a dooring accident doesn’t fall into that category, so they aren’t counted routinely.
    What little information we do have about dooring accidents is disquieting.
    First of all, thinking of them as routine is part of the culture. Volkswagen ran an ad joking about its padded doors a few years back. When a journalist in Oregon was doored and “merely” thrown to the ground and shaken badly, someone at the accident scene asked her, “Is this your first time?” These kinds of anecdotes tell you that dooring is common.
    Not only common: dooring is serious. Our friend John Brooking ( did a fairly modest amount of Internet research and counted 18 dooring fatalities over the years. Nonfatal dooring accidents outnumber the fatal ones by a _huge_ factor. 20 to one? 200 to one? Whatever it is… it’s a lot. And there’s nothing like a broken collarbone, closed-head injury, or lifelong chronic pain from the body’s reaction to a severe smack to make someone dislike cycling.
    We all know that bicyclists have the _absolute_ ability to have zero risk of dooring. They just have to ride outside the door zone. Many people are conditioned by fear, or by bikelane propaganda, to assume that this is difficult or that it requires some special skill. Nonsense. You ride. Get over the fact that overtaking traffic has to move around you. They’ll survive.
    Your legal options, should you be doored, or should you be injured as a result of swerving to avoid a dooring maneuver, range from murky to nonexistent.
    My stomach sours when I hear advocates say they want door zone bike lanes to encourage more cycling. How is it ethical to use the newbie cyclists’ tax money to pay to paint bike lanes that direct the cyclist to get injured?
    Much is made of the fact that cyclists ride in the door zone anyway. The response to that is straightforward enough: society _needs_ to find successful ways to teach cyclists how to ride safely. Rather than make excuses and lame facilities for unsafe riding, we must direct cyclists to ride safely. If one teaching approach doesn’t work, we need to try another one that does work.

    – John Schubert,

  4. As a cyclist who commutes 24 miles per day across Boston, I agree with Paul’s case against bike lanes in the door zone.

    I have been “almost doored” dozens of times, and no longer even stop to talk with the person, unfortunately. It’s come to be routine. I’m constantly trying to remain aware of whether there’s a car just behind me, in case I need to swerve out of the way of an opening door. I have a nervous anxiety and constantly look for signs of someone in a car ready to open the door. It shouldn’t have to be this way.

    Last year, I was actually doored, and got pretty bad cuts on my right hand, broke my shifting cable, twisted my wheel. They guy has the gall to yell at me as if it’s my fault. I yelled back and got $40 to fix my cable, but didn’t report it to police or anything. It’s too normal to take your lumps like that. The law doesn’t mean much. I tell people about the law when they open their door in my path, but many deny or disbelieve it and say I should be watching out for them.

    About the door-lane bike paths… in Cambridge, where the dooring death of Dana Laird occurred, there are lots of these paths.

    I was riding in one path on Mass Ave and then came to a construction area where the path was totally nonexistent, and a bus was ready to pull to the right after the intersection. So I pulled into the left lane on Mass Ave to get around the bus. I took the lane, as I think I have a right to do. The light was red so I stopped. The guy in an SUV behind me honked at me. He kept honking. I turned around, and he said “You’re not supposed to be in the car lane. I work for the traffic department, and there are bike lanes on this road. You have to be in the bike lane.” I told him I have a right to be in the road. He yelled some curses and told me I was dead wrong.

    Sometimes I take a lane because it’s the only safe option. I get yelled at by cars. I think that the presence of a bike lane may give them more of a feeling that the bike “has its place” and so it definitely should not be in the “car lane”.

    On the other hand, I have been yelled at by an angry cop to act more like a car. He said “Same road, same rules,” as his only explanation when I asked him how he thought I should be riding. He was not open to discussing it and threatened to arrest me when I asked for more details on some questions. I was not being a jerk or trying to instigate him. He must have been having a bad day or something, but that’s my experience on these issues. When I do try to ride with the “same road, same rules” mentality, then I get beeped at, yelled at, and even rushed by cars trying to “make a point” that I should not be on the road. But there really are places where it is necessary to take a lane to make a left turn or something.

    I like the shared lane markings. It gives more legitimacy to riding safely even when that means taking a lane for a hundred feet to make a turn, or to avoid a really bad door zone.

  5. Dear Paul,

    Thank you for your detailed work on this. I must admit, when I first heard read that there was a cycling advocate opposing bike lanes, I was a bit skeptical. However, you make a very reasoned argument here. I know that being doored is one of my largest concerns, but I know enough to worry about it. I think that you’re right to be concerned about cyclists who haven’t yet built that skill set, exactly the cyclists we’re hoping to attract with these measures. I love being able to bike throughout the city; let’s bring that to more people!


  6. Nice work and sound arguments, Paul. You’re an experienced rider and a realist when it comes to bicycling in the city. All city cyclists need skills and instruction; you really can’t be safe, sadly, by just swinging a leg over and hoping for the best in a designated lane.

    Despite riding for many years, I went down pretty hard last fall when I had to swerve suddenly to avoid a door. As you say, I was on the far left of an imaginary ‘lane’ (no markings existed) and was watching for heads in the driver’s seat, but the driver’s head must have been blocked by the headrest. Luckily, there were no vehicles to my left. And like Sage in the post above, the woman went crazy yelling at me. I’d like to think it was her fear – glad I didn’t understand her Portugese.

    Your best comment: “When you create a bike lane you create an expectation that bicyclists will ride *in* it (an expectation often enforced outside the law by vigilantes and even police officers). When the dimensions are so tight that the only safe place to ride is halfway outside the bike lane, you are creating a contradiction. (”We’ve installed bike lanes here to make you safer — now learn to ride half way outside of them.”) ”

    So please know that as a Boston native and someone who rides year round extensively on the roads of Boston and the burbs, the proposed lanes will only give some riders the illusion of safety – the illusion of safety. Better to have the gore stripes, advise all riders to slow down and expect each car door to be a threat, and yes, avoid narrow arteries like Center St when possible. I always take quieter roads, even if it means clipping in and out all the time. Good luck with your initiative – will support you where I can. Thank you for being a great neighbor.

  7. As a long time cyclist in Boston (early 1970s), I learned to ride on bike-unfriendly streets with no laws declaring our equal rights and responsibilities to follow traffic regulations. Much later I found that the survival strategies I had developed over years were validated by the book “Street Smarts”. There is no substitute for paying attention, watching like a hawk for movement in parked cars (look at their driver’s side mirrors) and at side streets, knowing where the moving vehicles are around you (helmet or eyeglasses clip-on mirror), giving large, clear, accurate signals, and as far as possible asserting your right to as much space in the lane as you need to avoid all curbside dangers. The biggest problem I see is indeed one of education, of cyclists and motorists alike. Every September we are inundated by tens of thousands of out-of-state college students, most of whom have no clue about riding in and with traffic. Part of the orientation process for area colleges and universities should be a primer on bicycle traffic laws; it might save me from getting hit while swerving to avoid an oncoming cyclist on the wrong side of the road…

  8. Charlie You’re right but your wrong. More riders won’t use sharos as they won’t get in the road and still ride in the door zone. It’s that simple. A lane is ultimately safer than nothing, plus it gets more riders and helps improve perception and acceptance. I haven’t followed the deal enough to comment anymore except to say that I think your work is undermining the process toward improving bicycling safety and acceptance in Boston.

  9. Paul, excellent article! Thanks for the cite on “Effect of cycle lanes on the proximity between motor traffic and cycle traffic”, looks promising.

    Thanks for the comments (exception of Phil)!

    @Phil: I don’t understand if agree or disagree with the article’s main point: Bike lanes on Jamaica Plain are questionable (dangerous to novice cyclists)?

  10. A great deal of information here, looks like you’ve been cracking open the books. First I want to say that I respect much of the work that you have done, Paul, for the biking community, and your support of many of our great biking groups.

    What I have a hard time with is your consistent opposition to bike lanes not just on Centre Street here but also on every street it seems you’ve ever commented on, including your successful opposition to bike lanes on the Rose Kennedy Greenway, and on Huntington Avenue. Correct?

    Also, I would appreciate a fair assessment of the facts. This should not be a contest of words, but of data. And I mean all the data, not just those that support one side of the argument.

    I encourage everyone to actually read the Hampshire Street Study at .

    First, it’s 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. I’ve been there, I think we’ve all been there where we say whew that was #%@! close!

    Then, you say “85% to 90% continued to ride inside the door zone.” But according to the histograms showing the distances for each street section in the study, the percentage of riders outside of the door zone was between 36.7 and 47.2 percent. The door zone in teh study was defined as 10 feet, as established by another study which found that 85 percent of doors opened to 9 foot 6 inches from the curb.

    And did you consider that doors that are opening quickly are by definition not completely open? Again, an inch of distance is a safety improvement when you consider thousands of accidents over time.

    All of this to me indicates that you may be a bit biased in how you present this data to the wider public, or in how you read it.

    This also goes for your citation of the British study “The effect of cycle lanes on the proximity between motor traffic and cycle traffic” which I also came across recently. This study showed that cars pass more tightly around cyclists. This finding is interesting, particularly on country roads without parking, like those it was held on. But crash data from the city of Cambridge (unfortunately Boston doesn’t record bike crash data) shows that our biggest problems are dooring and right hand turns.

    Now, if we’re going to be conjecturing, I’d like to join in at this point. Doesn’t it make sense that a motorist would see a bike lane and realize that they should a.) look back before opening their door b.) look back before taking a right turn.

    And of course all of this is before we consider what increasing the cycling rate will do for public health in terms of obesity, cardiovascular disease and all of the other ailments that are correlated to these. Even if a bike lane had the same amount of safety as no bike lane, we will have won in the bigger picture.

    The real health benefits from getting people to ride more often, and bike lanes are most often the first thing people say will help them ride more often or at all. This bears itself out in Portland and NYC as they are seeing big increases in their ridership long-term (the economy hit Portland this year) after building hundreds of miles of bike lanes.

    And to follow that up, both of those cities have seen their crash rates go down as ridership increased.

    There is no evidence out there that a city full of sharrows could do the same thing.

    Lastly, I’d like to share some crash data from NYC’s new bike lanes. These two streets are obviously very different from Centre, but I thought the improvements they are seeing there are very encouraging.

    Broadway – West 42nd Street to West 35th Street

    * Injuries to all street users down 50%
    * Reportable crashes down 49%
    * Injuries to pedestrians down 40%
    * Injuries to cyclists down 50%
    * Dates conducted: 8/1/05-1/31/08 & 8/1/08 to 1/31/09

    9th Avenue Complete Street – West 23rd Street to West 16th Street.

    * Injuries to all street users down 56%
    * Reportable crashes down 48%
    * Injuries to pedestrians down 29%
    * Injuries to cyclists down 57%
    * Dates conducted: 12/1/04 to11/31/07 & 12/1/07 to 11/30/08

    Thanks all, and thanks Paul for posting this comment.

  11. A bit tired when I posted, I left a few things out. One is a crucial bit of evidence from Hampshire Street, which is by and large approximately the same width as the section of Centre Street where bike lanes are being considered——and that is that the addition of the bike lane increased the amount of riders who were more than 10 feet from the curb by 8 percent.

    Another point is on the health tip. A fellow named Lars Bo Anderson led a study called “All-Cause Mortality Associated With Physical Activity During Leisure Time, Work, Sports, and Cycling to Work” in Copenhagen, randomly selecting 6954 subjects, interviewing them, and then following up with death records a mean of 14.5 years later.

    They found that even after adjustment for other risk factors, including leisure time physical activity, those who did not cycle to work experienced a 39% higher mortality rate than those who did.

    The interviews took place in the late 70s, which was right about when Copenhagen decided to start trying to get more people on bikes by building more bike lanes.

    And “all-cause” includes death by getting hit by a car. So the point is that overall, biking leads to longer lifespan, so the more people we get to do it the better, and bike lanes encourage people to do it.

    Of course, we still want to design lanes as safely as possible, and that is why I’m looking forward to seeing the designs that the city’s knowledgeable consultant brings forth. At that point we can have an informed discussion of how to mitigate any concerns we might have.

  12. Pete, I agree we should have “a fair assessment of the facts.” You’re right, the Hampshire St study found that bicyclists were 2.4 inches further away from parked cars in the two lane + bike symbol configuration, 2.8 with the left stripe only, and 2.0 with the two stripes and no symbol. They say that the 3 different treatments “were not significantly different from each other.” I think what I initially wrote is a fair summary, but I will change it to 2.4 inches.

    The important question is, were cyclists riding outside the door zone? But what’s “the door zone”? The study cites the San Francisco Shared Lane Pavement Marking Study ( “Data gathered in the San Francisco study determined that the 85th percentile of car doors observed opened to 9’6” from the curb
    (SFDPT data). Giving a 6” clear zone to the bicycle handlebar, the total width of the potential
    door zone would be 10 feet.” (top of p. 4) But Van Houten and Seiderman made a mistake. They calculate the door zone as the width from the curb to the (right edge of the) bicycle handlebar, but on the bottom of the same page they tell us that they are measuring “The wheel path of bicycles in the roadway.” In other words, they are not accounting for the width of the bicycle. The San Francisco study they cite assumes that bicycles are 2′, and that the bicyclist’s wheel should thus be a half-width (1 ft) farther from the curb, for a total of 11′ (including the same 6″ shy distance). This is all diagrammed in the image of the shared lane marking, which comes from the same SF study (

    So Von Houten and Seiderman are off by a foot. At one point in the discussion they implicitly acknowledge this: “For cyclists to travel completely outside the full door zone, the left handle bar would be in the travel lane.” Since the left bike lane stripe is 12′ from the curb, the cyclist’s wheel would have to be a bit more than 11′ from the curb for a 2′ handlebar to be partly in the travel lane.

    We have established that the bicycle wheel has to be 11 ft, not 10 ft, from the curb to be out of the door zone by their own definition with correction for failure to account for the width of the bicycle. Now go look at the figures showing distribution of bicyclist wheel position. Very few are to the right of the 11′ mark (the exact figures are not shown).

    Moreover, as I said, you can make a strong case that the bicyclist should be at 12′ from the curb. Recall that the SF study reported only the 85% percentile of door extents. I would prefer to go with the 95th or even 99th, which would bring the odds of being with range to 1 in 20 or 1 in 100 instead of 1 in 7. Also bike handlebars can be more than 24″ wide.

    Inexplicably, in the discussion Van Houten and Seiderman suddenly start talking about bicyclists “9 and 10 feet from the curb.” This allows them to show that 85% or more of the bicyclists in many of the recording locations were more than 9 ft from the curb. But this cutoff has no meaning, even using their own (erroneous) 10 ft limit. It would be nice if they calculated how many were more than 11 ft and how many more than 12 ft. You can eyeball this from the charts: very few were riding that far out.

    I would love to see the data behind the NYC bike lane and cycle track stats you cite. I have also seen those figures, but not any description of what exactly is being compared.

    I will post more about bike lanes and right turns later.

  13. Ya, but even if you put it at 11, which I don’t agree with. There is still the fact that more people on average rode further from the cars than before the lane was striped.

    Obviously, you ride in the road, I ride in the road, but this is not about us. This is about everyone. If it moves everyone a bit further away from the doors, maybe we save a life somewhere down the line.

    This is about lives. I know you must believe in your position, but I hope you are open to new information.

    By the way, another cyclist got hit on Huntington today.

  14. Lying with artists’ renderings. Gee, I’ve never seen that before.

    Now I know that when presented with a drawing, I should always pull out a ruler and check the scale.

    But how do we make the public care? They just see pretty pictures and think that being picky about things like scales is pure pedantry.

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