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It's more the opposite special case -- we have a hard cap on our ability to consume transport, which is why it's usually a good idea to build more. You can own

It's more the opposite special case -- we have a hard cap on our ability to consume transport, which is why it's usually a good idea to build more. You can own 2, or 20, or 200 houses, and block the usage of them from anyone else. (induced demand with unlimited consumption). You can own 2 or 20 or 200 cars, but you can't physically drive more than one at a time. This is a hard cap on transportation consumption (you can't literally drive two cars at once, you can't be going to two different places at the same time) This is why the induced demand philosophy doesn't work for cars. Demand for transit has a low hard cap. If your society is broken such that there's lots of latent unserved demand, it will artificially look like there's induced demand happening near the beginning. But that demand will vanish as soon as you get close to a functional level of capacity. For a more practical example: If you could get to Japan in 20m, then you might choose to do so, And if you could go to lunch in Japan, you can't also be having lunch in California, which means you can't be waiting in traffic on the Bay Bridge. The induced demand philosophy obsesses over the "downside" of improved transit (that you get to go to cooler places faster and cheaper), but intentionally ignores the upside (that you free up the capacity of whatever you had chosen to do prior, and now no longer do).

amanaplanacanal 5y ago
I doubt we could build enough capacity for all cars to be on the road at once, which seems to be where the hard cap would kick in.
dalbasal 5y ago
Think of travel consumption in terms of kms, not cars, trains or whatnot. Waiting in a traffic jam is not traveling. You can own 20 houses, not renting them out. People just wouldn't, because it's pointless. You could also own 97 iphones, or 400 pairs of jeans. Latent demand just that people would buy more if it was cheaper. That's normal, not broken. IDk what "artificially look like there's induced demand happening" means. If we could we would travel many more KMs. 1000s of times more, if teleporting existed and made travel instantaneous. The cost of travel, is largely time.
- maxsilver 5y ago
  >IDk what "artificially look like there's induced demand happening" means. Urbanists sometimes intentionally undercount existing traffic and overcount later traffic, to try to paint public transportation infrastructure in a bad light. "We widened the public transit freeway by an extra lane each way, and now it handles ~33% more people per day. See, freeways make traffic, public transportation is bad" The public transit freeway in this instance did not make any new traffic. It moved traffic from other sidestreets, and it allowed people who were underserved by transport to finally get served by transport. But nothing new was created here. It's like saying, "Hospital A has 100 sick patients and is full, but we can't build a new Hospital, because it will make more sick people". And then a new hospital B gets built, and they say, "see, before we had 100 patients, now we have 200 sick patients, the new hospital induced more sickness!" But in truth, the Hospital didn't "make" any sickness, it's treating patients that were previously uncounted or not getting treatment they needed -- that's why we wanted to build a new hospital in the first place. > If we could we would travel many more KMs. 1000s of times more, if teleporting existed and made travel instantaneous. The cost of travel, is largely time. Right, and that acts as a hard cap. You can't travel to two places at a time, and you aren't going to want to spend every second of your life traveling somewhere. So, unless you think Winnebago's are going to be a thing everyone lives and works out of 24/7/365, there's a very explicit hard cap on transportation usage. If you make a teleporter between California and Japan (for example), then an urbanist could paint that as "your teleporter is bad, because it induced demand for trips to Japan". But it didn't -- for every one person in your teleporter, there's one less person on an international flight. Even if your teleporter makes trips to Japan more popular and common (because it's now faster + cheaper to get there), it still doesn't break this hard cap, those trips are disappearing from somewhere else. I live in Michigan, I would normally never grab lunch in Japan. But if I leave to go to Japan for lunch (using your new teleporter), then I can't be driving on US-131 to pick up lunch back at home (a totally normal thing I would do today). I'm not going to suddenly eat 2 lunches just because your teleporter exists, so even though someone would argue you have "induced demand" for trips to Japan, you haven't really done so, you've just taken other trips and converted them. The only way "induced demand" will ever apply to cars, is if that hard cap is broken somehow. Driverless cars, for example, could actually induce demand, since a car no longer has to have a person in it to take up traffic space, and plenty of people would send driverless cars around, there's no longer a natural hard cap on transit usage.
supertrope 5y ago
More lanes are built. More people move in and select their jobs and housing based on being able to drive between them in 30 min. Congestion returns. Red queen race. We're applying a linear solution to an geometric problem. The underlying argument behind induced demand is if you spend $XX million USD on widening a highway from 6 lanes to 8 lanes and now capacity has gone up NNNNN people per hour, that can be a worse investment than spending $XX-YY on million commuter buses going down an HOV lane to get the same NNNNN capacity boost, or maybe spend the same amount but get NNNNN+MMMMM boost. We should optimize for people per hour, not cars per hour. Work from home gets us another step further: instead of moving office workers bodies downtown so they can sit at a desk, why not eliminate the commute entirely?
- maxsilver 5y ago
  > More people move in and select their jobs and housing based on being able to drive between them in 30 min. Cool, that means they no longer live in their old city, so the transportation infrastructure of their old city is now freed up. No congestion was created, it just got moved (by place and/or time). No "demand" was "induced".

amanaplanacanal 5y ago

I doubt we could build enough capacity for all cars to be on the road at once, which seems to be where the hard cap would kick in.

dalbasal 5y ago

Think of travel consumption in terms of kms, not cars, trains or whatnot. Waiting in a traffic jam is not traveling. You can own 20 houses, not renting them out. People just wouldn't, because it's pointless. You could also own 97 iphones, or 400 pairs of jeans. Latent demand just that people would buy more if it was cheaper. That's normal, not broken. IDk what "artificially look like there's induced demand happening" means. If we could we would travel many more KMs. 1000s of times more, if teleporting existed and made travel instantaneous. The cost of travel, is largely time.

maxsilver 5y ago
>IDk what "artificially look like there's induced demand happening" means. Urbanists sometimes intentionally undercount existing traffic and overcount later traffic, to try to paint public transportation infrastructure in a bad light. "We widened the public transit freeway by an extra lane each way, and now it handles ~33% more people per day. See, freeways make traffic, public transportation is bad" The public transit freeway in this instance did not make any new traffic. It moved traffic from other sidestreets, and it allowed people who were underserved by transport to finally get served by transport. But nothing new was created here. It's like saying, "Hospital A has 100 sick patients and is full, but we can't build a new Hospital, because it will make more sick people". And then a new hospital B gets built, and they say, "see, before we had 100 patients, now we have 200 sick patients, the new hospital induced more sickness!" But in truth, the Hospital didn't "make" any sickness, it's treating patients that were previously uncounted or not getting treatment they needed -- that's why we wanted to build a new hospital in the first place. > If we could we would travel many more KMs. 1000s of times more, if teleporting existed and made travel instantaneous. The cost of travel, is largely time. Right, and that acts as a hard cap. You can't travel to two places at a time, and you aren't going to want to spend every second of your life traveling somewhere. So, unless you think Winnebago's are going to be a thing everyone lives and works out of 24/7/365, there's a very explicit hard cap on transportation usage. If you make a teleporter between California and Japan (for example), then an urbanist could paint that as "your teleporter is bad, because it induced demand for trips to Japan". But it didn't -- for every one person in your teleporter, there's one less person on an international flight. Even if your teleporter makes trips to Japan more popular and common (because it's now faster + cheaper to get there), it still doesn't break this hard cap, those trips are disappearing from somewhere else. I live in Michigan, I would normally never grab lunch in Japan. But if I leave to go to Japan for lunch (using your new teleporter), then I can't be driving on US-131 to pick up lunch back at home (a totally normal thing I would do today). I'm not going to suddenly eat 2 lunches just because your teleporter exists, so even though someone would argue you have "induced demand" for trips to Japan, you haven't really done so, you've just taken other trips and converted them. The only way "induced demand" will ever apply to cars, is if that hard cap is broken somehow. Driverless cars, for example, could actually induce demand, since a car no longer has to have a person in it to take up traffic space, and plenty of people would send driverless cars around, there's no longer a natural hard cap on transit usage.

supertrope 5y ago

More lanes are built. More people move in and select their jobs and housing based on being able to drive between them in 30 min. Congestion returns. Red queen race. We're applying a linear solution to an geometric problem. The underlying argument behind induced demand is if you spend $XX million USD on widening a highway from 6 lanes to 8 lanes and now capacity has gone up NNNNN people per hour, that can be a worse investment than spending $XX-YY on million commuter buses going down an HOV lane to get the same NNNNN capacity boost, or maybe spend the same amount but get NNNNN+MMMMM boost. We should optimize for people per hour, not cars per hour. Work from home gets us another step further: instead of moving office workers bodies downtown so they can sit at a desk, why not eliminate the commute entirely?

maxsilver 5y ago
> More people move in and select their jobs and housing based on being able to drive between them in 30 min. Cool, that means they no longer live in their old city, so the transportation infrastructure of their old city is now freed up. No congestion was created, it just got moved (by place and/or time). No "demand" was "induced".