September 2, 2016
People will live in electric vans
Reading an article about people in Silicon Valley living in cars (didn’t save the reference, go look for it) and noticing that there was no plan to build new housing fast enough to meet demand, it occurred to me that (necessity being the mother of invention) there would be innovation in the world of cars-for-living-in.
I thought about this a little more, and realized that electric vans (camper vans, minivans, step vans, not sure exactly what) were likely to hit the sweet spot for this. So many things go better with electricity, especially nowadays. Electricity runs lights, computers, fans, phones, electric blankets, in a pinch it can even run air conditioning. And it does all this quietly, with no smells. Gas powered cars can supply a little power for a little while from their batteries, but they’re small, and the usual way to recharge them is to run the engine when there is otherwise no need. Mechanical constraints to get power to the wheels usually force the floor of the car (or van) relatively high above the ground, reducing interior headroom.
Electric cars have comparatively huge batteries, and will certainly be able to refill at charging stations (and some employers even provide these for free, at least for a little while more), or at relatively low cost from someone else’s electric power, and there is always the option of solar (especially in sunny places like Silicon Valley), especially on the squarish roof of a van. Rooftop solar wouldn’t provide enough energy for a lot of driving, but it would cover consumption by electric amenities. Because power can be distributed to the wheels through wires instead of mechanical axles, the floor of the van can be relatively low to the ground (this is a really good idea anyway for a delivery van) which provides a lot more headroom inside.
It’s possible that a self-driving van could also dodge overnight parking restrictions by driving very slowly on low-traffic streets, automatically pulling over whenever faster traffic approached from behind (5mph or less, to conserve energy, minimize motion for sleeping passengers, and maximize safety).
If I can think of this, I’m sure someone else is already working on this. Anywhere that artificial restrictions on housing supply cause prices to spike, this could be an option.
After a little more thought, this: “Neighborhood Electric Vehicles”. A weight budget of 3000lbs, but no need for a high-strength frame or collision crumple zones gives you room to work with (old VW vans weighed much less than that).
June 24, 2016
On June 22 Cambridge held a public meeting on traffic in Inman Square. I did not attend. I did receive a pointer to the presentation. The next day, a woman on a bicycle was killed in Inman Square, perhaps first doored, certainly run over by a landscaper’s truck.
Slide 4, I see counts of “traffic volumes” measured in “vehicles per day”.
Which of the following is “vehicles”:
- bicycles only?
- cars and trucks only?
- bicycles and cars and trucks?
I see no pedestrian counts, which seems like a major omission.
I also see no breakdown by turns, which makes it difficult to know how much of a priority to place on turning traffic.
I also don’t see any information about existing light timings.
For slide 13, the only group for whom “increase efficiency” is a concern is “Vehicle”, and I suspect that really means “Motor vehicle” since “Bicycle” is a separate category. This seems like a major omission, since you have apparently not measured either the bicycle traffic or the pedestrian traffic, we don’t know if optimizing motor vehicle efficiency reduces the total time wasted at this intersection, and it might well compromise safety. Lacking any other information, I think we must assume that each person traversing this intersection is equally important.
It’s also important to notice that attempts to “increase efficiency” for motor vehicles here could be pointless. This intersection doesn’t exist in isolation; it is connected to the rest of Cambridge, which is also filled with traffic jams. In contrast, both bicycles and pedestrians flow freely through the rest of Cambridge (I bicycle commute on Broadway or Hampshire every working day of the year, I have video) so impediments removed here would result in actual gains.
One efficiency problem that could be addressed with no infrastructural changes is locally-greedy misbehavior by drivers; people frequently enter the intersection without a clear path to exit it, resulting in a blocked box when the light changes (bicycles are less affected by this; again, I have video). Drivers also speed fruitlessly (later to be passed in a line of stopped traffic by a fat old man on a huge heavy bicycle, so truly useless speeding), endangering everyone. In both cases, the remedy for locally-greedy misbehavior is enforcement; tickets for blocking the box, tickets for speeding, tickets for running red lights. Automated enforcement is probably more cost-effective than staffing the intersection every day at rush hour.
Another thing I saw no mention of was the role of parking in reducing safety. The door zone is a constant worry to cyclists, and the space allocated to parked cars also reduces options for creating safe places for cyclists to ride.
Other questions that need answering:
- I know that buses use Hampshire. How many people use those buses, and how much delay (summed over all the bus passengers) results from that delay? That’s another thing we should optimize.
- There’s a lot of bike traffic on Hampshire, especially at rush hour. If we knew the range of trip distances for people traversing Inman Square in cars (especially at rush hour), we might get some idea of the potential number of bicycle commuters that would use Inman Square if were less dangerous and more pleasant (it is one of the more significant unpleasantness bottlenecks in Cambridge).
Given what looks like a severe case of car-centric tunnel vision by whoever prepared these slides, I think that someone needs to start over again, perhaps doing the mental exercise of banning cars and seeing what sort of intersection results. (That’s not quite a serious proposal for an intersection design, but it is definitely a serious proposal for being sure that something other than cars-cars-cars is considered.)
My choice for a starting point would be to de-emphasize traffic “efficiency” for single-occupancy vehicles since those are the least-efficient users of scarce road space, the most needy in terms of a clear path to travel, and relatively dangerous to other people on the roads. Buses are space-efficient, very safe for their passengers, necessary for the less-able, and a good backup choice in nasty weather. They’re not a good thing to crash into, but their drivers are trained professionals, and risk-to-others is amortized over all the passengers on the bus and thus is not that large per passenger. We should remove enough cars from the road to ensure that buses are not impeded. Both bicycles and pedestrians are very space-efficient and though neither mode is risk-free, they are very safe for other people, and they’re also able to cope with narrow paths and impediments that completely block automobiles. I would therefore do as much as possible to make those two modes attractive. When I look at all the somewhat-unused space in Inman Square, my reaction is to try to find ways to use that space make things better for pedestrians and cyclists, instead of trying to use it as more places for cars to drive on.
Videos of Inman Square:
June 9, 2016
Hypothesized mechanisms for “safety in numbers”
Safety in numbers is a cycling safety rule that says that the more people ride bikes, the safer each rider will be. Hypothesized mechanisms include (1) driver familiarity – because drivers more often see bikes on the road, they become better-trained to see them on the road and (2) driver empathy – because so many drivers also ride bikes, they are more aware-of/concerned-about bicycle safety issues. (Here’s a nice pile of pointers to papers, tracked down by a real live researcher.)
I think both of these mechanisms are entirely possible, but riding an actual bike in actual traffic in actual crowds of cyclists, I’ve noticed what looks like other ways that greater numbers provide safety. In at least one case I’ve captured it on video. The difference between these mechanisms and the others that are hypothesized is that they are extremely short term – “safety in numbers” can appear whenever there is a biking crowd and disappear as soon as it disperses. These are also somewhat more likely in crowded urban areas and depend somewhat on the existence of traffic jams.
The first mechanism I might call “schooling” (after Bike Snob’s “shoaling” and “salmoning”). Bikes riding in a line are schooling, and for several common cycling hazards, most of the risk is borne by the lead fish, and the rest get a free ride. If someone in a parked car is not looking for bikes and is about to open their door, but then a bike zips by, it’s not unreasonable that they would be startled, and maybe then look to see if it was clear – and if the bikes are schooling, all the followers get the benefit of that. The dooring risk is almost entirely on the lead cyclist. Similarly, cars pulling into or across traffic represent a threat only to the lead cyclist, and very little to the ones in the rear. A line of bikes is also somewhat protective against right hooks, since those usually occur when a driver thinks they can overtake a bike and turn right, or forgets the presence of a single bike. With a line of bikes, once the first is across the side street, it is obvious to the driver that a right turn is not possible.
A second method is less obvious, but safety decreases markedly in the range of speeds between the slowest and fastest typical commuters. A low-speed (below 10mph) crash is stupidly survivable; you can almost step off your bike as it falls down. A high-speed crash (above 20mph) is far more likely to send you to the hospital or worse. Bike lanes at rush hour tend to run single file for some distance, usually because the bikes are hemmed in between parked cars on the right and “parked” cars on the left. Inevitably, some riders will be slower than others, and the inability to pass then compels the would-be-faster riders behind to slow down until they can pass. This makes them safer, whether they like it or not. This, I’ve seen on video, where I play the role of impatient rider. The probability of this delay and the difficulty of passing both rise pretty quickly once there’s more than a couple of riders delayed behind a slow leader.
After dark, a school-of-fish also multiplies the effectiveness of any lights that cyclists might be using. Just considering use of lights and not, if an unlit cyclist pairs up with one using lights, they can obtain most of the safety benefit of the lights. When two cyclists both have lights, the variations in their movement or in the flashing style of their different lights will create additional visibility over a single cyclist; for example, one cyclist’s flashing light might draw attention, but the other’s steady light might allow a driver to accurately locate the pair. Not nearly as many cyclists ride at night, but bicycle lighting use in the US is not nearly as good as it should be, so there’s plenty of room for this to help.
I don’t know if I’m typical, but if I’m riding at night and overtake another cyclist without lights who’s not too much slower than me, I’ll slow down to give them the benefit of my lights. I’ve even done this with a (impressively fast and competent) rollerblader caught out too late on the local multi-use path.
The interesting (to me) thing about these is that they can work in the US, they take no time to work, and they take no change in driver empathy or enlightenment. And if a crowd of bikes disassembles, then the safety effects do as well. The effects should appear most often at rush hours, when the largest number of bikes are on the road and when they are most hemmed in by traffic.
A historical/hysterical note is where the idea for safety-in-numbers comes from, and why we assume its existence even when we’re not entirely sure how it works. Once upon a time, when Effective Cyclists were peddling their prescriptions for safer cycling (ride in the road, in traffic, just like the “vehicle” that bicycles legally are, and that legal status is a good thing for which the EC movement certainly deserves some credit) the counterexamples of “the Dutch” and “the Danes” came up, where many people often ride bikes on lanes entirely separate from auto traffic, with crash fatality rates 5 times lower than ours. The EC people were very good at finding and/or interpreting studies that “proved” that if only the Dutch would get rid of their separate facilities, they would be even safer than they are now, that in fact their extraordinary safety must have some other cause. (This might even be true, but nobody’s ever managed to get more than about 1% of the population to bike in an “Effective” style.)
And what was the obvious difference that might be the cause of that anomalous safety? “Numbers”. It must be “Safety in Numbers”, assumed to exist to fill a (huge) gap between theory and reality. This was convenient for the Effective Cyclists because they got to continue to feel correct about their prescriptions (“just you wait, once everyone here rides bikes, we’ll be the safest cyclists on the planet!”) but now this same hypothesized mechanism is used to justify creation of cycling-specific infrastructure that Effective Cyclists hate (“we’re tired of waiting, EC is phenomenally unpopular and we’ll never get the numbers that give us the safety we want if we do it your way. And by-the-way, global warming, particulate pollution, pedestrian deaths, urban congestion delays, traffic noise, and public health, we need this now. Infrastructure will get butts in saddles and safety-in-numbers ‘proves’ that they’ll be safe.”)
May 7, 2016
I recall once figuring that the capacity of a single track of subway was substantially higher than a lane of traffic. This is how that is calculated for a real live subway (the MBTA Red Line, also roughly applies to Orange and Blue lines which run similar equipment.)
redline_cars_per_train = 6
Source: Wikipedia red line article
redline_trains_per_hour = 60/4.5 = 13.3
Source: 2014 MBTA Blue Book, page 17.
Headway is 8 or 9 minutes at rush hour on each of the Alewife/Ashmont and Alewife/Braintree lines, or 4.5 minutes on average on the shared portion of the line.
redline_ppl_per_car_policy = 167 redline_ppl_per_car_crush = (267*74+260*58+277*86)/(74+58+86) redline_ppl_per_car_seated=(63*74+62*58+52*86)/(74+58+86)
Source: 2014 MBTA Blue Book, page 18.
167 is the policy people-per-car. Seated and crush capacities are averages over the red line fleet.
seated_rush_cap = redline_ppl_per_car_seated * redline_cars_per_train policy_rush_cap = redline_ppl_per_car_policy * redline_cars_per_train crush_rush_cap = redline_ppl_per_car_crush * redline_cars_per_train seated_rush_cap * redline_trains_per_hour => 4,671.5596 policy_rush_cap * redline_trains_per_hour => 13,360 crush_rush_cap * redline_trains_per_hour => 21,526.6055
Compare this with a lane of traffic. Rule of thumb is that you get one car every two seconds, or 1800 cars per hour, and an average of 1.2 people per automobile, or 2160 people per lane per hour. Simple seated subway capacity at rush hour is double that, so-called “policy” capacity is 6 times that. Crush capacity, which I’ve seen and not much liked (“nobody takes the subway, it’s too crowded”) is just shy of 10 times the capacity of a lane of traffic.
And understand, this is far from the theoretical capacity of a subway line, it’s just what is actually obtained on a real subway in a real city at rush hour. Run longer trains (requires longer platforms, a completely doable thing) and you can add capacity. Run trains more frequently, and you raise capacity – the London Underground appears to manage 24 trains per hour at rush hour on the Northern Line or not quite double the Red Line’s frequency.
Re-doing the numbers at the London Underground’s rate for scheduling trains:
seated_rush_cap * underground_trains_per_hour => 8,408.8073 policy_rush_cap * underground_trains_per_hour => 24,048 crush_rush_cap * underground_trains_per_hour => 38,747.8899
At the Underground rate, “policy” train packing carries 11% more people than “crush” packing in the current system. And the theoretical “crush” capacity is the equivalent of 18 lanes of traffic.
March 26, 2016
Earlier this week, I was riding my bike home on a road with a bike lane, and came up to an intersection where the car at the front looked like it was planning to turn right (based on position in lane and angle of wheels) but was not signaling a right turn. The intersection has no advanced stop line for bicycles, just a plain old stop line and crosswalk. And understand, me going first is a completely legal thing, there are two lanes, straight traffic has right-of-way over turning traffic.
This presented several choices. I could stop far enough back that if the driver intended to turn right, they could easily do so (except that they would probably get hung up by pedestrians in the crosswalk and would stop midway, blocking the bike lane and delaying me). If they did manage to turn right quickly, there’s no guarantee that the driver behind might not try to barge on through with their own right turn; that’s happened, I even have video of someone doing this. Or, I could pull up to the stop line, and hope that if they did decide to turn, that they’d notice my presence in time not to hit me, and also not try to just make their turn through intimidation. Or, (and this is what I did) I could stop a little bit in front of the stop line – technically illegal, though I’ve never, ever seen this particular law enforced and drivers violate it constantly – and position myself so that the driver could hardly help seeing me, and even if he didn’t or if he decided to go anyway and there was a collision, I’d land on the hood of the car – relatively safe for me as collisions go, relatively damaging to the hood of the (expensive) car.
I hope it’s clear that this is no way for a normal person to ride a bicycle. I do so because I’ve learned it over the years and it’s no longer difficult, but to think that I would explain this to someone else as “useful tips for riding in traffic” is insane. This is similar to knowing that “it’s okay to ride closer to parked cars in a residential permit parking zone, because people move those cars only about once a day”. Or, “practice riding through potholes no-hands, so you get really good at controlling your bike on our crappy crappy roads”. I’m not making any of this stuff up, I do these crazy things, our roads are messed-up enough that it helps.
I’m not sure how this gets fixed. Safety-in-numbers is some mitigation; with enough people on bicycles, it becomes obvious that there’s bike traffic to the right and bike traffic through intersections and bike traffic past car doors, and the normal distribution of aggression among bicyclists insures that a few of them will help carve out space for the rest. I don’t put much stock in driver education; there’s not that much in it for the drivers, and it’s work to constantly be looking around for bikes. We could pretend to do more enforcement, but in practice the majority has zero appetite for that (evidence: we don’t vote for more enforcement, despite continual infractions and drivers killing thousands of themselves and other people every year). I think I’d like it if we adopted some modern Dutch infrastructure; a lot of that is designed to get rid of these designed-in conflicts and make it easier to see what’s going on. I have some hope that robot cars might be helpful; tedious rules like “always signal a turn at least 10 seconds or 3 car lengths before the turn” are what computers are for, as is “look for bikes in all directions always”.
February 27, 2016
I both drive cars and ride bikes, and for years I didn’t think much about how much driving a car impairs all your senses, as well as your ability to communicate. To hear how other people talk about traffic and safety, I think I’m not the only person to miss this.
Where this usually comes up is in discussions of rolling stops, and stop-then-go at red lights. The claim from cyclists (and this claim is absolutely true, which is why I’m writing this) is that they generally can see and hear better than people in cars, and thus are in a better position to judge if it is safe to go or not. This is one of the several justifications for the Idaho Stop Law.
So, vision. Someone riding a bike is as tall as they are standing up, if not taller. To stop, most people must hop off the saddle because they sit too high to reach the ground with their feet. Modern sedans tend to be about 4-and-a-half-feet tall (I just measured a Civic and a Camry), so whoever is sitting in them is shorter than that. On a bicycle, seated, your head is about 3 feet back from the front edge of the bicycle, but it’s easy to lean forward to within about a foot of the front. In a car, leaning forward gets you to the windshield, which is five feet back from the front of the car. Add to that whatever fog or dirt happens to be on the windshield and the windows, plus the various pillars and mirrors and fuzzy dice, and I hope it’s clear that the cyclist has a far better view of what’s around.
Next, hearing. Luxury cars are actually marketed for their ability to make you deaf to the world. That ought to be enough right there, but I’ve actually mentioned this to a degreed+prestigious colleague whose snap reaction was “no, I can hear okay in a car”. No, really, you can’t. Even without luxury soundproofing, cars have noisy engines, ventilation fans, tire noise, often a stereo, and quite often their windows are up. All these things act to block exterior sound. On a bicycle, the default is that you hear everything. There’s wind noise when you’re moving, but stopped at an intersection there’s nothing between you and the world and the bike is silent.
And you might like to think that maybe hearing doesn’t matter–after all, we let people who are deaf drive and ride bikes–but it certainly does. When I approach intersections, I can hear cross traffic coming before I can see it; that’s redundant safety information, which is a good thing. I can hear cars approaching from behind, and tell if they’re slowing or swinging out into traffic to pass, and I can judge the size of the car or truck as well (big trucks without sideguards are very dangerous). For pedestrian safety being able to hear matters, because I can carry on a conversation with the people around me. “I see you”, “go ahead, it’s a crosswalk, I’m stopping”, and of course “oops, sorry”. I can communicate with other cyclists, “there’s a blind woman walking ahead of you” (in the dark). All the sound signals that we’re supposed to legally make when approaching pedestrians are useless when approaching cars because drivers are effectively deaf. All the communication that’s easy with people around us is impossible with people in cars.
People on bikes also see more because of their ability to always position themselves near an intersection before stopping. That means we always get to see the light cycles and light timings, and even if we haven’t learned them all yet ourselves, we can see how other cyclists react to them. We don’t need to catch sight of landmarks as we drive through the intersection, because we always have plenty of time to look around at the front. Once you know the usual timing for a light (easily derived from countdown pedestrian timers on the street and cross street – which you can see because you are stopped at the intersection) you can also judge from quite a distance the appropriate speed to make the next light, which allows you to moderate your speed to only what is adequate to catch the green. Lower speeds make for easier pedalling, and are also safer.
I had meant to make a much longer rant about “windshield vision”, but I think this is good enough for a start. You might ask yourself, if you could drive and fool yourself into thinking that you weren’t half-blind and mostly-deaf, and not realize what you were missing stuck back in a line of traffic, if you might not be self-fooled about some other things. If your reaction to the facts stated here is that they’re the crazy opinions of one of “those cyclists” – don’t forget, I am a licensed driver, I drive often enough, I own a car, and this is true of most adults riding bicycles (knowing this stuff makes driving a lot less fun. Don’t expect any auto advertising to mention this ever).
Bonus sensory deprivation video, in case you still don’t believe me: watch the second driver in this video roll right over a bicycle and a bicyclist’s foot, and not be able to believe she did it. Said bicyclist has right of way, in clear daylight, riding straight on a straight road, wearing a dayglo-yellow jacket, with a front flashing light. The second driver did not see, did not hear the crash, did not hear the crunch of the bike as she drove over it, did not hear the guy she was running over yelling at her.
It occurred to me a few days after posting this that “people on bikes behave unpredictably” is consistent with “people on bikes make decisions based on information I don’t have”. Probably not the only explanation, but worth thinking about before jumping to pejorative conclusions.
January 1, 2016
I did a round of noodling in a spreadsheet to try to get a feel for how different ways of carrying people or cargo damage roads. The formula for damage is the sum of the cubes of the wheel loads; crudely, the gross weight of a vehicle cubed, divided by the square of the number of wheels. This can lead to some pretty non-intuitive results — city buses in particular are non-intuitively bad for roads . Overall the most surprising thing is that even when results are calculated either per-passenger or per-pound, you end up needing a log scale to display them meaningfully; heavy vehicles are that bad for roads.
I’m not quite sure what to do with this information; there are other things to optimize for besides road damage. For example, it would not surprise me in the least if a semi-trailer were more fuel-efficient per-pound than a human on a bike; bikes are efficient, but we do have to eat to run them and food is quite often energetically costly. Similarly, though bicycles are far safer for pedestrians than cars and trucks, per pound of cargo they will lose most of their advantage against delivery vehicles (the comparison is quite tricky; a cargo bike can easily carry 100 lbs in addition to its rider, and 250 is not out of the question, and such large bicycles are even less likely than “normal” bicycles to travel at pedestrian endangering speeds. Contra that, a human pedaling a loaded cargo bike has an incentive to not stop because it takes quite a lot more energy to bring that larger weight back up to speed).
Note that a single-occupancy vehicle still fails badly on efficiency and safety metrics, but trucks of various sizes need not.