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.

I wrote at critique of the Cambridge study at:
http://bicyclingmatters.wordpress.com/critiques/dzbls-in-cambridge-ma/

and of the San Francisco Study at:
http://bicyclingmatters.wordpress.com/critiques/san-franciscos-shared-marking/

Both of these studies are junk science.

Wayne

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.

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 (http://www.sfmta.com/cms/uploadedfiles/dpt/bike/Bike_Plan/Shared%20Lane%20Marking%20Full%20Report-052404.pdf): “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 (http://bicycledriving.org/wp-content/uploads/2010/03/shared-lane-placement-from.gif).

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.

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.

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 http://www.cambridgema.gov/~CDD/et/bike/bike_hamp_study.pdf .

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.

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)?

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.