This is a half-baked theory based on no particular expertise of mine, but I’ve been reading and thinking about safety for a while now (perhaps decades).  I have come to think that one contributor to driver irritation with cyclists is that drivers are already driving about as fast as they can think (if not faster) and the sudden appearance of something out of the ordinary like a cyclist in traffic is the straw that breaks the cognitive camel’s back; the driver is no longer able to keep track of everything that is going on and they don’t like it.

Several things led me to this.  One was things like the awareness test video, where it is made obvious how our attention can become so focused by cognitive load that we will overlook what is right in front of us. Another is my use of daytime running lights; I started doing this years ago because when I built my own lights I left out the off switch (it’s just another point of failure).  With lights on all the time I am more visible and less likely to surprise, and it seemed that I had many fewer unpleasant interactions with drivers.  They were still often-enough clueless and no more likely to obey traffic laws, but they seemed to almost never be angry with me.

A third thing is the experience of riding the bike itself.  My bike is relatively tall (has a high bottom bracket) and I am slightly tall (6′) I am riding upright, and rarely going even 20mph.  I can see around me much better than when I am driving, and because I am almost always moving at a reasonable pace I have plenty of time to consider what I see.  And once you get used to this, the lack of it is unpleasant — when I’m driving, I notice that I’m deaf, and I don’t like it (I roll down the windows, whatever the weather — what’s more important, safety, or not getting a little rain blown in the window?), and I notice that I’m short and can’t see as much, and I don’t like it, and I notice that stuff is happening too quickly to pay proper attention to it.  I think most only-drivers are accustomed to a different baseline than I am, but when they fall off that baseline they don’t like it, same as I do, and blame the distraction for their irritation.  In my case, I blame the car that I am driving, in their case, they blame the cyclist, pedestrian, or whatever it is that happened to cause their cognitive overload.

Another application of this is in devising safety rules.  One rule that serves me well on my bike is to count the number of potentially unpredictable things (dogs, small children).  One is usually not a problem because I can swing wide of it.  Two, I should slow down some, depending on details.  But three is more than I can reliably track; I should slow down to a walk, if I cannot put a safe distance between me and the children/dogs.

Or, when approaching a crosswalk with pedestrians in it, how do they know that I intend to stop?  Sure, I could slow down, but that means that they have to track me long enough to know that I am slowing down, and what if I wait till the last minute — that all combines to add an unnecessary cognitive task for those pedestrians.  That’s rude.  So I slow early so it is easier to see that I know I should stop, and I signal so that they don’t have to track, and I aim the bike behind their path so they can see that I think they should be crossing.

Field trip to NYC

October 1, 2015

So I’m attending a conference in NY on Friday, took the train down Thursday and spent the afternoon at the NY office, took Citibike to get there from Penn Station and then back again to the hotel.  Most of my riding was on 8th and 9th Avenues, which have nice segregated bike lanes.  I observed the following:

– sidewalks in NY are too small.  Pedestrians regularly spilled over onto the bike lanes, and it’s because the sidewalks are crowded.  Obviously the sidewalks need to be larger, because we cannot make pedestrians smaller, and they are the overwhelming majority here.

– no matter what anyone says, bicycles are not terrifying relative to cars.  I didn’t see any pedestrians walking in the flow of traffic because the sidewalks were too small.

– salmoning is about 100x more common here than in Cambridge (MA).  I see it there in-my-face about once a month, here, I’d say at least a dozen times in less than an hour of riding.

– in the places where the bike lanes were not segregated (by a line of parked cars) everything dissolved into nonsense.  Cabs drove in the bike lane, bikes rode in the cab lane.  The should rip it out and do it again.

– but where the lanes were segregated, it worked really well.  It was quite comfortable, I did have to take care to not hit people on foot, but that’s not hard (I’m on a Citibike, not exactly racing along).

– cars driven in NY should have their horns removed.  I know the horn law in this state, horns are only for safety, “the light is green but you’re not moving” is not a safety issue. Period. (Go ahead, try to argue the case that it is, make a fool of yourself.  Stopped cars are the safest cars.)

I saw the arguing aftermath of a pedicab-bike collision — didn’t understand why on earth the guy on the bike was pressing the point because I saw nothing hurt and nothing broken, but he was.  I blocked more than one NY taxi from making a right turn when it came into conflict with the bike lane.  I saw one person on a bike who was trying to make a big deal about clearing pedestrians from the bike lane (“ha ha, she has got to be kidding…”).

1000 miles to the new job.

October 1, 2015

(written in July, now it’s October) I got a new job 4 months ago, now in Kendall Square all the time.  I only bike to work, unless I work from home (done that 2 or 3 times so far) and I even commute by bike when I visit the mother ship in Mountain View.  In 4 months I accumulated just about 1000 miles to work, a combo of neighborhood streets, bike lanes, cycle track, sharrows, and fitting in wherever it is appropriate.  October update — 1750 miles now, about 250/month, and writing this from NYC where I rode Citibikes to/from the NY office today.

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I’ve noticed that car drivers on the internet often think they are qualified to lecture “cyclists” on how to be safe. This is ludicrous, given that the average driver is 10 to 20 times as likely to kill a pedestrian as the average cyclist, with a similar ratio for serious injury, and the cyclists are mostly car-owning licensed drivers anyway. “But cyclists break traffic laws”. Number one, they only do so about as often as drivers – people are people, we all make mistakes and take shortcuts, and we all also overlook the faults of our own tribe and are hypersensitive to those of “the other” – and number two, if you really think that cyclists DO break laws at some unusually high rate, then that means that laws have not much at all to do with true road safety. Recall that bikes are 10 to 20 times less likely to kill or seriously injure pedestrians than cars – that’s safety.

So, if cyclists don’t obey laws, what do they do that makes them so much safer? And wouldn’t it be great if drivers knew about this, so they could do these things too, and be much more socially responsible? I’m sure they’d really like to know, so I will BikeSplain safety for them:

  • around bikes and peds, 20mph is plenty. Not 21. 20. And in general, never build up speed you don’t need; if the light is red, why not coast as soon as you see the red, instead of going fast and then braking at the last moment. Speeding-then-braking is a waste of energy and poses unnecessary risk to others.
  • do not use a larger vehicle than necessary for the errand. 100lbs (a large cargo bike) is adequate for 3 kids, groceries, etc, if you’re only traveling a few miles. This holds true even when choosing one car over another, if you have a long or hilly errand, or if you are handicapped in some way; an SUV is over 3 times more likely to kill someone else than a regular-sized car.
  • windows down, stereo off. You need to be able to hear what’s going on around you. With the window up and stereo on you’re effectively deaf, and you’re certainly less able to hear than a cyclist using earbuds (yes, someone has tested this).
  • if you’ve been drinking, it’s good to always pass a small challenge of coordination before embarking on a journey to be sure that you’re sober enough to drive a car. For example, if you cannot keep a bicycle upright for more than a block or two, you are surely too drunk to drive. So if you’ve been drinking, even a little, be sure to ride a bike first as a test to see if you’re sober enough to drive.

Almost every cyclist on the road obeys the rules above, and that’s the main reason why they’re so much safer than drivers. The one exception is people who are training to race – they often travel faster than 20mph and are less safe for pedestrians, but fortunately they are a small minority of urban cyclists.

Many cyclists follow additional safety rules to otbain even more safety. I use these rules myself, and I’ve seen other people do the same:

  • never use your horn or bell. Use your brakes instead. Think about all the stuff that has to go right for your horn to make things safer, versus the certainty that you see something going wrong and could start slowing down right away to either prevent it or mitigate it. With the windows down and stereo off, you might be able to even talk to the people around you.
  • if you can imagine a potential crash, act to reduce its risk and/or mitigate it if it occurs. No free pass just because you think the other guy is breaking a law. How sure are you about traffic laws? And so what if they are breaking the law, is dead an appropriate outcome? Is that guy with the leaf blower going to stumble backwards into the road? If you see a teenaged boy on a bicycle or driving a car, what are they odds he might do something irresponsible? Drive as if that might happen, and be prepared to keep it from causing a crash.
  • reduce speed limit by 5mph for each child/dog (up to 3) near your path, i.e., 15, 10, 5. It’s unlikely that you can keep track of 3 unpredictable moving objects at once, and even trying will distract you from everything else you should be watching. So slow down, to give yourself more time and to mitigate the harm of any crash that might occur.

In the spirit of “Same Roads, Same Rules”, I think these are good rules for everyone to follow, both in cars and on bikes.

Cost of a lane of parking

September 6, 2015

The Green Line Extension in Somerville and Medford is part of the (legally mandated) environmental mitigation for the Big Dig freeway-burying project. Like other parts of the Big Dig, there have been cost overruns and bloats in estimated cost, and it is now projected to cost $3 Billion for 4.3 miles of trolley rail.

Another way to spend money would be to remove parked cars from roads and use the extra space to establish dedicated lanes for buses (and perhaps bicycles, not sure how well that works in practice). But what would that cost?

Generously, I estimate 500 cars per mile of road – 10560 feet of road (both sides) divided by 20 feet per space, minus a dab for hydrants, driveways, cross streets, and 500 is a nice round number. The Metropolitan Area Planning Council estimates $20,000 or more to construct an urban underground parking space, not counting land. That gives a construction cost of $10,000,000. For land, compare with the Alewife parking garage, which uses 5 acres for 2733 cars, none parked underground or on the first floor. This suggests an acre, and hopefully the ground floor can have some more productive use than car storage. In Somerville, extrapolating from some recent home sales on Zillow, an acre of land costs $11 million. Call it $15M for the sake of conservatively round numbers.

Thus, the round-numbers replacement cost of a mile of both-sides street parking is $25million, or about $50,000 per space, plus annual maintenance (according to the MAPC) of up to $2000 per year. There are plenty of related costs and benefits – if there’s only one garage per mile, some people will have long-ish walks, but on the other hand the parking will be mostly covered and thus not require shoveling out in the winter. It’s likely that parking would be distributed into smaller hunks to simplify land acquisition for garages and to reduce the walking distance.

$50,000 for a parking space may sound like a lot of money, but compare it to the cost of an 8’ x 20’ piece of land at $15 million per acre. Do the math, and you get about $55,100 per parking space.

Doing this benefits us in several ways. Because buses can move more quickly, they provide a more valuable service to their users. Because buses can cover the same distance in a given amount of time, either service can be more frequent for the same cost, or else fewer buses are needed to provide the same service intervals. Street plowing and cleaning become easier, and emergency vehicles can flow more freely during rush hour. Crossing streets becomes slightly safer because parked cars will no longer obstruct views between pedestrians and drivers; each can more easily see the other. Removing parking also eliminates the cause of bicycle dooring (20% of the crashes recorded in Cambridge) and both improved visibility and the availability of the bus lane as a refuge from traffic are likely to improve bicycle safety.

There is an economic side-effect of making the cost of parking more salient; if the city is paying off a bond on a parking structure or has a budget item for parking structure maintenance, that will encourage a critical comparison of the cost of parking versus the cost of alternatives. Right now the default treatment of parking is as if it is “free”, as if there were not even any tradeoffs to be made. This doesn’t sound like a good thing to someone who is currently benefitting from free or subsidized street parking, but from an economic point of view it is likely to lead to a more efficient allocation of resources if we recognize their costs.

To return to the Green Line, its original $2Billion cost estimate would be adequate to remove parking from 80 miles of streets.

It turns out driving to work is indeed a public health issue. I did the math a hair more carefully, and over the entire population it looks like driving to work causes about twice as much early death as cigarette smoking. From OECD, Cycling, Health and Safety, pdf page 44, table 1.2:

“Relative risk expressed as a ratio of all cause mortality of cyclists compared to non-cyclists after controlling for confounding factors (age, gender, education, etc.) – e.g. a relative risk result of 0.70 indicates that a cyclist has a 30% reduction in risk of death compared to a similar non-cyclist.”

Location Relative mortality risk (cycling/non-cycling) Confidence interval Study
Copenhagen 0.72 0.57–0.91 Anderson et al, 2000
China 0.79 0.61–1.01 Matthews et al, 2007
China (HA) 0.66 0.40–1.07 Matthews et al, 2007
Finland 0.78 0.65–0.92 Hu et al, 2004
Finland (HA) 0.69 0.57–0.84 Hu et al, 2004

(HA) = “high activity”

A “relative mortality risk” of 0.79 (call it 0.8 for ease of math) means that in a given year a cyclist has only 80% of the risk of dying of a non-cyclist – or if you view the choice to not ride a bike as the abnormal behavior, a non-cyclist has a 25% (0.2 added to 0.8, 25% of 0.8) higher risk of death.

This is not as bad as smoking per-person – that about doubles (adds 100%) to your mortality risk – but only about 18% of the population smokes, and 86% of the population drives to work. Weighted by exposure, driving to work is a larger public health problem than smoking. (If 18% of population quit smoking, 18% of population cuts their 2x normal death rate in half, a 9% drop. If 86% of population quits driving to work and starts walking or biking, 86% of population cuts their death rate by 21%, an 18% drop.)

Note that this says nothing about whether we make it easy for people to stop smoking or stop driving so much. Absolutely it is hard, I have friends and relatives with commutes that are completely impossible on a bicycle, or walking, or transit. We have chosen to make it hard for people to live healthier lives, and we should stop doing that. We need more transit from far-flung suburbs. We need safer streets to bike on, both in suburbs and in cities. We need greater density closer to work. Because our towns can’t necessarily afford greater density because of the property tax expense of serving all those extra people, we need to change how we fund things like education. Broken policy should be fixed, not used as an excuse.

Smugness Accomplished!

August 15, 2015

I had once lamented that, though it is tiny, bicyclists do benefit from some small subsidy for their use of the roads, and that this undermined our goal of attaining peak smugness. Somehow it escaped my attention that gasoline is only taxed with a “gas tax” and not with a “sales tax” – yet bicycle chains, tubes, and tires (the three items that are consumed every few thousand miles of bicycle use) are taxed, with a sales tax. If the sales tax is 5%, even the heaviest cyclist (e.g., me, on a loaded cargo bike) need only spend about $20 per year on these consumables to be adequately taxed for their use of the road.

It ought to be obvious, but we’re done here. Bicycles not only pay the full cost of their wear and tear of the road, they pay more. Drivers only pay about half – the rest is subsidy from other taxes besides gas taxes, excise taxes, and tolls. Smugness accomplished!


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