4 ms·

Two people traveling 30 mph in a 10 by 50 foot rectangle have a throughput of 116 people per minute. If that same 10 by 50 rectangle holds 100 pedestrians walki

by rsj_hn 5y ago

Two people traveling 30 mph in a 10 by 50 foot rectangle have a throughput of 116 people per minute. If that same 10 by 50 rectangle holds 100 pedestrians walking at 3 mph, it will have a throughout of 528 people per minute which is 5 times better, But because they are only going at 3 miles per hour, it will take them 2 hours to walk 6 miles instead of 12 minutes, which is a factor of 10 loss of efficiency. Thus the loss in terms of throughput is more than offset by the gain in terms of time saved. Then when you add other factors such as protection from weather and ability to carry heavy things, you understand why streets have vehicles in them instead of just relying on pedestrians. Only in those situations where time has no value or distances are very short is the pedestrian option more efficient than the vehicle option.

Wowfunhappy 5y ago
But you can't drive anywhere close to 30 mph in a crowded city center. A cyclist can probably move more quickly than a car.
- rsj_hn 5y ago
  Look you are arguing about the parameters, so I guess you acknowledge there is a trade off. Maybe in one city it's 2 miles you are willing to walk. Maybe in another, only 1 mile, or 4 miles. Point being, there is a reason people don't walk everywhere, which is that there is a space/time trade off. Once you understand this trade off, you'll also understand why we give more room to cars than to pedestrians, and why people walk short distances but not long distances. And I haven't even begun to model all the positive externalities of vehicles -- everything from letting trucks filled with goods stock your "local" coffeeshop, and workers to drive to that coffeeshop. And when the plumbing gets backed up or the ice-machine needs repair, someone will drive to that coffee shop -- right by your house -- and fix it, all so you can have a walkable neighborhood in which you can sip coffee and complain about cars. And there are other positive externalities including more price competition and thus cheaper goods, reduction in geographic monopolies, increases in homeownership rates, etc. I say this as someone who doesn't even own a car, but I recognize that I am extremely privileged to be able to work from anywhere and live in an expensive urban center where everyone spends long hours in their cars driving to me and catering to my needs, from delivering my groceries and packages to driving from the burbs to my neighborhood to cook me dinner. I am at the top of a huge pyramid reliant on vehicles -- and I know it. I'm not going to say "Let them eat cake". A good life-tip is that if you ever come up with some model of society that makes everyone look like they are doing something irrational, then odds are that your model is wrong, not that society is wrong. It can happen that you really are smarter than the system and that you've predicted all the important long term consequences of your proposals and correctly weighed them -- but it almost never does. And not for something as obvious as sidewalks being able to hold more people than cars per square foot. We need far fewer would-be social optimizers, and far more humility in these discussions, as our world is flooded with bad models and bad ideas.
  - Wowfunhappy 5y ago
    > A good tip is that if you ever come up with some model of society that makes everyone look like they are doing something irrational, then odds are that your model is wrong, not that society is wrong. Well, but it could also be a case of "tragedy of the commons". Everyone is acting rationally on an individual level, but a collective change would be to everyone's benefit. I know people who drive big SUVs even though gas is more expensive not because they like big SUVs, but because they're worried if they don't drive a big SUV, they're more likely to die in a crash with someone who does. The result is, of course, even more SUVs.
    - rsj_hn 5y ago
      Yes, there can be some tragedy of the commons issues, but a lot of the time, that's really an issue of a stable versus unstable equilibrium. You would be surprised by how many people insist on an unstable equilibrium and ask government to try to stabilize it, which often ends up being quite expensive. But it does happen. However most tragedy of the commons issues are not new and there are already established ways of dealing with them. In the specific case of SUVs, almost all SUVs sold are actually lifted sedans. They don't have much worse mileage or weigh more than the corresponding sedans. Nor are they better in crashes. It's more of a culture war item where some people really hate those who drive the SUVs -- soccer moms, etc. Here the issue is that a lower center of gravity (and a stiffer ride) creates better handling, but an SUV is more comfortable and is easier to get in and out of. And it usually features a soft suspension. So there are a lot of car enthusiasts that hate SUVs because it's a rejection of their values, and a lot of Europeans that prefer wagons to SUVs are offended by someone wanting to sit higher up. Now yes, there is a situation in which higher cars make it more valuable to sit higher up, but that difference of being 1 foot higher doesn't really destroy visibility, it's psychological. The most popular SUV -- RAV4 has a height of 5.6 feet -- whereas the most popular sedan of 2020 (Camry) has a height of 4.77 feet. That 1 foot difference is not going to destroy visibility and does not represent some out of control thing. The difference in weight is about 100 pounds (3500 for Rav4 and 3400 for Camry). RAV4 gets 30mpg combined -- same as the Camry. These are not huge differences to justify the rage many have at SUVs. Just give the SUV in front of you a bit more room and your visibility will be fine, nor does the RAV4 force other people to get a RAV4 due to collisions.

by rsj_hn 5y ago

Wowfunhappy 5y ago

But you can't drive anywhere close to 30 mph in a crowded city center. A cyclist can probably move more quickly than a car.

rsj_hn 5y ago
Look you are arguing about the parameters, so I guess you acknowledge there is a trade off. Maybe in one city it's 2 miles you are willing to walk. Maybe in another, only 1 mile, or 4 miles. Point being, there is a reason people don't walk everywhere, which is that there is a space/time trade off. Once you understand this trade off, you'll also understand why we give more room to cars than to pedestrians, and why people walk short distances but not long distances. And I haven't even begun to model all the positive externalities of vehicles -- everything from letting trucks filled with goods stock your "local" coffeeshop, and workers to drive to that coffeeshop. And when the plumbing gets backed up or the ice-machine needs repair, someone will drive to that coffee shop -- right by your house -- and fix it, all so you can have a walkable neighborhood in which you can sip coffee and complain about cars. And there are other positive externalities including more price competition and thus cheaper goods, reduction in geographic monopolies, increases in homeownership rates, etc. I say this as someone who doesn't even own a car, but I recognize that I am extremely privileged to be able to work from anywhere and live in an expensive urban center where everyone spends long hours in their cars driving to me and catering to my needs, from delivering my groceries and packages to driving from the burbs to my neighborhood to cook me dinner. I am at the top of a huge pyramid reliant on vehicles -- and I know it. I'm not going to say "Let them eat cake". A good life-tip is that if you ever come up with some model of society that makes everyone look like they are doing something irrational, then odds are that your model is wrong, not that society is wrong. It can happen that you really are smarter than the system and that you've predicted all the important long term consequences of your proposals and correctly weighed them -- but it almost never does. And not for something as obvious as sidewalks being able to hold more people than cars per square foot. We need far fewer would-be social optimizers, and far more humility in these discussions, as our world is flooded with bad models and bad ideas.
- Wowfunhappy 5y ago
  > A good tip is that if you ever come up with some model of society that makes everyone look like they are doing something irrational, then odds are that your model is wrong, not that society is wrong. Well, but it could also be a case of "tragedy of the commons". Everyone is acting rationally on an individual level, but a collective change would be to everyone's benefit. I know people who drive big SUVs even though gas is more expensive not because they like big SUVs, but because they're worried if they don't drive a big SUV, they're more likely to die in a crash with someone who does. The result is, of course, even more SUVs.
  - rsj_hn 5y ago
    Yes, there can be some tragedy of the commons issues, but a lot of the time, that's really an issue of a stable versus unstable equilibrium. You would be surprised by how many people insist on an unstable equilibrium and ask government to try to stabilize it, which often ends up being quite expensive. But it does happen. However most tragedy of the commons issues are not new and there are already established ways of dealing with them. In the specific case of SUVs, almost all SUVs sold are actually lifted sedans. They don't have much worse mileage or weigh more than the corresponding sedans. Nor are they better in crashes. It's more of a culture war item where some people really hate those who drive the SUVs -- soccer moms, etc. Here the issue is that a lower center of gravity (and a stiffer ride) creates better handling, but an SUV is more comfortable and is easier to get in and out of. And it usually features a soft suspension. So there are a lot of car enthusiasts that hate SUVs because it's a rejection of their values, and a lot of Europeans that prefer wagons to SUVs are offended by someone wanting to sit higher up. Now yes, there is a situation in which higher cars make it more valuable to sit higher up, but that difference of being 1 foot higher doesn't really destroy visibility, it's psychological. The most popular SUV -- RAV4 has a height of 5.6 feet -- whereas the most popular sedan of 2020 (Camry) has a height of 4.77 feet. That 1 foot difference is not going to destroy visibility and does not represent some out of control thing. The difference in weight is about 100 pounds (3500 for Rav4 and 3400 for Camry). RAV4 gets 30mpg combined -- same as the Camry. These are not huge differences to justify the rage many have at SUVs. Just give the SUV in front of you a bit more room and your visibility will be fine, nor does the RAV4 force other people to get a RAV4 due to collisions.