November 10, 2013
is a comment containing this link
to a study by Kenneth D. Cross and Gary Fisher which is cited by John Forester in Effective Cycling to support his claim that accidents where the cyclist is hit from behind are not a large risk, and thus we should not be afraid to ride with traffic and even somewhat in the part of the road where automobiles commonly travel. I believed this claim for decades, because presumably he would represent that study fairly, and not cherry pick or distort the data to support his position.
What can I say, I was young and naive, right?
Surprising to me, when you read the cited statistics, you discover that things are not exactly the way Forester claimed. Accidents in which cyclists are hit from the rear (Problem Type 13, p. 33) cause 23.4% of the fatalities. That’s not at all the impression you would get from reading Forester. It is true that 70% of these fatalities occur on narrow, rural roads at night, and alchohol is often involved, but that still leaves 7% of all fatalities in the non-narrow+rural+night case of hit from behind.
Is 7% large? Probably. Riding against traffic poses a significant risk of injury (p. 174, a factor in 20.1% of injuries) but only a 4.8% risk of a fatal injury.
In contrast, sidewalk riding in the presence of driveways (Problem Type 8, p. 31) is not nearly as dangerous as portrayed by Forester — no fatalities! (Yes, there are injuries, 5.3% of the total).
And thus my opinion of Effective Cycling takes another lurch downwards. The study itself is interesting; what I read there makes me feel happy about my decision to equip my bike (and all my kids’ bikes) with hub-powered lights that are always on when the bike is rolling; again and again, visibility is a factor.
November 10, 2013
In a comment exchange on some random liberal blog, a transit advocate was mysteriously opposed to bicycles-as-transit. He never completely explained why, but I think he was making assumptions about road damage and congestion that assumed a linear relationship to weight. However, that’s just not so. Damage-per-wheel is at least proportional to the cube of the weight on the wheel, if not the fourth power. It’s very non-linear, and non-intuitively a heavy vehicle with many wheels can do less road damage than a lighter vehicle with just a few.
Turns out, a city bus can do a LOT of damage, and per-passenger, it does over twice the damage of even a single-occupancy SUV. A plan-loaded city bus is almost as bad for roads as a fully loaded semi truck, and a crush-loaded city bus is worse. Whether you calculate it as marginal damage per passenger, or average damage per passenger, a bus passenger is hundreds of times more damaging to the road than even a fully-loaded cargo bike, and thousands of times more damaging than someone merely carrying themselves on a bicycle. Even the marginal road-damage cost of the first passenger to board a bus is a little bit worse than the road-damage cost of a single-occupancy SUV.
I’m not at all sure that these costs are rolled into the published “costs” of transit. Note that these are not the only costs; there are congestion costs, parking space costs, fuel costs, risk-to-others costs, risks-to-rides costs. But the road damage costs are really large.
(And if someone knows more about this than I do, do please check my math, I am working from published sources and conservative estimates. This was surprising to me.) Read the rest of this entry »
November 10, 2013
Standard US anti-cycling claim: “We’re too spread out, not like those dense European countries.”
Here’s the copy-and-paste from Calca:
density(area, population) = population/area http://en.wikipedia.org/wiki/New_York_metropolitan_area NYCMetro_area = 13,318 NYCMetro_population = 23,508,600 density(NYCMetro_area, NYCMetro_population) => 1,765.175 http://en.wikipedia.org/wiki/Netherlands Netherlands_area = 16,039 Netherlands_population = 16,819,595 density(Netherlands_area, Netherlands_population) => 1,048.6686 http://en.wikipedia.org/wiki/Massachusetts Massachusetts_area = 10,555 Massachusetts_population = 6,646,144 density(Massachusetts_area, Massachusetts_population) => 629.6678 http://en.wikipedia.org/wiki/Denmark Denmark_area = 16,562.1 Denmark_population = 5,602,536 density(Denmark_area, Denmark_population) => 338.2745
And if you notice, there’s a whole lot of Western Massachusetts that’s relatively empty (and also relatively hilly), but that works against the “we’re spread out” claim; if the west is sparse, then the east must be even denser.
And no, we do not have a uniform transit policy across the nation — how many subways are there in Montana or Alaska? We do what’s locally appropriate.
October 21, 2013
Or, rules for breaking the rules.
When I go grocery shopping I often ride to Fresh Pond Mall in Cambridge. Getting there on Concord Avenue is easy; there’s a nice cycle track that’s almost entirely unbroken, adjacent to a sidewalk, together they are 12 feet wide.
Unfortunately, on the return I’m supposed to ride on the other side; the “cycle track” there is cut by many driveways, usually full of dirt and debris, and just plain less pleasant. So instead, I salmon on the nice side. I have a two-part logic to justify this. First, 12 feet wide is the same width as the Minuteman Trail (in places the trail is only 10 feet), which accommodates bidirectional walking and cycling with only an instruction to “keep right” (which is even vaguely followed), so it should be possible here, too. However, because some Bright Boy at the Cambridge Planner’s office decided to invent their own rules and post them (and even encode them in asphalt and concrete), people often follow posted rules that make suboptimal use of the space. Second, I have rules for breaking rules that make it “okay” (okay if you subscribe to my rules, that is).
Rule #1 is that when salmoning, you yield to everything, because you’re breaking the rules.
Rule #2 is that other people should not even imagine that they need to break the rules to accommodate your breaking the rules.
Rule #3 is that when in doubt, give priority and deference to pedestrians; if any crash should occur, it’s not the pedestrian bringing energy and momentum to the crash.
Rule #4 is that you can stop if it is necessary to maintain rules 1-3.
So, normally you ride in the cycle track, not the walkway, since pedestrians should not even need to think about what you might do. If there’s an oncoming bicycle, no pedestrians, then you use the walkway, leaving plenty of room for the bike. If there’s oncoming bike AND pedestrians, then you stop, in the walkway (now you are a pedestrian, and you are where you belong) till the traffic clears. And if there’s an oncoming bicycle in the walkway, maybe you stop, because two wrongs not only doesn’t make a right, it does make the chances of a crash through misunderstanding a good deal higher.
June 22, 2013
I needed 3 16-foot 2x4s, and I was not quite sure it would be a good idea to carry them on the bike. So I used the car, which fortunately is old and does not have a finish much worth caring about. It was a bit of a load:
. I didn’t have to worry about cracking the windshield, since it was cracked already and unlikely to survive the next inspection (which is due in about a week).
So when I got it home, I decided to try it on my bike, since I needed to haul it around back anyhow, and I would take a few spins around the cul-de-sac to see how it handled. It’s safe to say that I’ve hauled worse; it was very long and I had to do a 3-point turn instead of the usual U-turn, but the wobble was well within my abilities to steer.
Next time, most likely I’ll take the bike. I think I will have a look at the wider-kickstand hack, because right now it’s too lopsided to balance. Done. (Yes, I had the parts in my box of “you never know when you might need…”) Bike stands, loaded:
June 18, 2013
Among our excuses for not riding bicycles is that America is too spread out. This explains why we don’t ride cross country very often, but not why we don’t ride to the grocery store. In fact, a whole lot of us live in places that are quite dense. I attempted to graph this before using 2000 Census data and “50K areas” but I was unhappy with the result, both because of my errors and because 50K area leaves out a lot (I live in a town of 25000, for example).
Happily, with new data, organized by non-overlapping zipcode, I can solve both those problems. One sixth of us (52 million people) live in places denser than 5362 per square mile; the next sixth, denser than 2786 per square mile, the next sixth, denser than 1292 per square mile (that’s the median density for our population; half of us live in zipcodes less dense than that, too). With all the zipcodes included it’s clear that many of us live in plenty-dense places.
I’ve tagged the graph with densities of towns and cities near Boston, mostly inside 128, plus all of Boston, and also plus three European cities known for their relatively high bike trip share. I added some other US cities for comparison. Read the rest of this entry »
We went for a ride on the tandem today (actually, months ago, I sat on this for a while), into Cambridge, to Inman Square, and we had to get there reasonably quickly. The conclusion from the stoker S was “that was not much fun; I would do it again on the tandem, but not on my own”. For all the claimed bike-friendliness of Cambridge, they’ve got a long long way to go.
The two main problems are (1) that the calm routes are not direct, and the direct routes are not calm and (2) avoiding nasty traffic and tight spots requires improvisation that is technically illegal, which makes it unsettling to many people, and hides it from official discussion of routes and infrastructure planning.
And people need to understand — me, personally, it’s good enough, but I’m a member of the biking 1% who tolerates traffic. The rest of you people, if you think to yourself, “gee, I’d like to commute to work on my bike, I need to lose 20 pounds, and I HATE parking in Cambridge” — until Cambridge gets serious, it’s probably not going to happen for you. You’ll try it, and hate it. And it’s not your fault; it’s Cambridge’s fault. Read the rest of this entry »
June 18, 2013
This is the sort of stuff that drives me nuts. Some guy (you know it was a guy) saved himself, oh, a minute or two by not writing an error message correctly, and that means that I (another guy) must spend many, many minutes in a debugging McGuffin to try to figure out what’s really going on. Read the rest of this entry »
March 30, 2013
Biking across Cambridge remains problematic despite their various efforts to improve things. The least-challenging routes are nowhere near direct, and the more direct routes contain uncomfortable stretches and a few random dangers. Sometimes fixing trouble spots is hard — for example, there has to be a tradeoff between car flow and bicycle flow, or between parking and bicycle flow.
But sometimes, making things better for bicycles requires no tradeoff. An example of this is the crosswalk from Cambridge Common to Harvard Law School across Mass Ave. Technically it’s “not for bicyles”, but in practice it is, because the other routes through Harvard Square are crowded and full of cars.
This crosswalk has two problems. First, it’s not big enough; there’s often enough pedestrian and bicycle traffic that people pile up and get in each other’s way. This can lead to conflict between bikes and peds, which is not good. Second, it’s not intuitive. For whatever reason, the crosswalk is divided into segments that don’t all “go” at the same time. A cyclist who’s not aware of this (who makes the completely reasonable assumption that it’s all go) runs the risk of sprinting right into the front of a car with a green light.
The problematic lane is marked with a blue dashed line. The other lines, pink and blue, show (what could be) the two basic cycles for this light.
My solution to this problem comes in two parts. First, the pedestrian crossing must be all “go” at the same time. The light then has two cycles, pink and blue. One problem with this is that it requires a very long walk signal for the slowest pedestrians to get all the way across, and this will probably interfere with the car traffic flow. Instead, run the walk signal on a shorter cycle that only gives the slowest walkers time to get half-way across. However, at the island where they are expected to stop and wait, provide a nice place to wait (shown in the picture with a green box). That means covered to protect from the weather, and with substantial barriers to protect from passing traffic (in the case of parents with small children, to help keep children getting into traffic). This should include a bench, so people can sit and rest.
Second, because the faster pedestrians and cyclists will certainly plan to cross in a single cycle, make the crossing wide enough (and mark it) so that they can spread out, move fast, and avoid conflict. There’s no particular reason that the crosswalk needs to be as narrow as it is; there is an ample stretch of unused space, and it should be dedicated to making this crossing nicer for people who aren’t driving.
All the crosswalk signals must have countdown timers, so that people crossing can properly estimate whether they can make it across in a single cycle or not.
March 23, 2013
Dear Burlington Planners,
I don’t live in Burlington, but I work in Burlington, and I often ride my bike to work, and what keeps me from riding to work more often is the abominable cycling and pedestrian facilities that you (Burlington) provide. I think you can and should do better. In addition, a friend of ours has a somewhat-special-needs son who works at the Dollar Tree; he cannot drive, but with a few road improvements in Burlington he could probably ride a bicycle to work, which would be better for everyone involved. Read the rest of this entry »