15 ms·

This problem generalises and is why building more, bigger roads is not a silver bullet solution to congestion. More road capacity pushes people towards using ca

by DC-3 5y ago

This problem generalises and is why building more, bigger roads is not a silver bullet solution to congestion. More road capacity pushes people towards using cars for all their journeys so increases traffic, sometimes to the extent that congestion is worsened not lessened.

triska 5y ago
This phenomenon is known as the Jevons paradox, named after British logician, economist and statistician William Stanley Jevons: https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox
- dalbasal 5y ago
  Traffic/travel is a relatively special case though... We have a near unlimited ability to consume transport. If you could get to Japan in 20m, I would probably pop over for lunch right now or Vladivostok for a Sunday stroll. As transport improves, people work/shop/etc further from home. Commuting range is measured in time, not kms. So, capacity (eg traffic) tends to be the balancing force. That's more than the typical Jevons Paradox, I think.
  - Tomte 5y ago
    For traffic you've got the even more interesting Braess's Paradox: https://en.wikipedia.org/wiki/Braess%27s_paradox https://en.wikipedia.org/wiki/Braess%27s_paradox
  - maxsilver 5y ago
    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.
  - GekkePrutser 5y ago
    This is true. If I could go to New Zealand for a weekend break in 20 minutes for cheap I'd be there every weekend..
martingoodson 5y ago
This is called ‘induced demand’. Surprisingly, the opposite happens when you remove road capacity - which is called ‘traffic evaporation’. It’s why taking road space from cars and reallocating it to bicycles is often more successful than predicted: https://nacto.org/docs/usdg/disappearing_traffic_cairns.pdf https://nacto.org/docs/usdg/disappearing_traffic_cairns.pdf
- kqr 5y ago
  Removing capacity from infrastructure is a solution that works when you want to discourage use of that infrastructure. If that's not the case, I only know of one other solution: charge directly for usage. That way you can set the price such that demand stays at a high level, but at one supported by maximum available capacity. If someone knows of a different solution, I'd like to know -- I have an induced demand problem in a type of infrastructure that I would like to operate at high capacity, and charging for it would be unconventional to the point of making it hard to find support for that solution.
  - goodpoint 5y ago
    Charging money for access to transportation is very politically biased: people with low or no income are effectively denied transportation while people with high income are not discouraged. This is how slums are created. > If someone knows of a different solution, I'd like to know Some cities have areas that allow unlimited access to locals and deliveries and limited access to others (X times per year)
    - kqr 5y ago
      Yes, that's a problem. I've debated with myself over what would be a fair division of "limited access" in my case but not arrived at a satisfactory solution. Anything I can think of will devolve into an inefficient, sucky, inofficial market. (This is why I'm contemplating an efficient, less sucky, official market in the first place.) To be clear: the infrastructure I'm working on isn't transport, but it'd still be odd to only allow paying users. I was thinking two similar copies of this piece infrastructure, where one is priced to avoid congestion, and the other will be as congested as induced demand allows. I'd like the discussion to stay general because I suspect any solutions will be reusable.
atatatat 5y ago
In a city, yes. In a suburb, the solution isn't anything except building more and better roads. People aren't bicycling 10-15 miles to the grocery. They should be, but, that's a different societal problem.
- oscardssmith 5y ago
  In suburbs, we shouldn't have grocery stores be that far from people.
  - OwlsParlay 5y ago
    Welcome to American zoning laws, sadly.
- adamjb 5y ago
  ...are there really places in the US that are considered suburbs where the nearest place to get groceries is 10-15 miles away? That's appalling.
  - other_herbert 5y ago
    I think most people would call that “the middle of nowhere” or out in the boonies... or it could be a new area that is growing.. 15 miles from groceries is too far to be called a suburb
    - masklinn 5y ago
      > I think most people would call that “the middle of nowhere” or out in the boonies... Not in the US. In the US "in the middle of nowhere" is grocery runs of 50+ miles. 15 miles is a "far out" suburbian hellscape e.g. https://i1.wp.com/cdn-images-1.medium.com/max/1080/1*AEfVhyvwGyqDmnZcAQfIGg.png?resize=398%2C264&ssl=1 https://i1.wp.com/cdn-images-1.medium.com/max/1080/1*AEfVhyv... or https://bostonglobe-prod.cdn.arcpublishing.com/resizer/h2N-h_4kbaMMps_4ou05IwXb6tM=/1024x0/arc-anglerfish-arc2-prod-bostonglobe.s3.amazonaws.com/public/Z4IGXQBGAII6HALMQUI2U2GARA.jpg https://bostonglobe-prod.cdn.arcpublishing.com/resizer/h2N-h...
choward 5y ago
It also encourages people to live further from where they work which also adds to traffic.
Wowfunhappy 5y ago
Of course, it does also mean more people are able to use the road (or canal). So it’s not a complete loss, even if it doesn’t have the intended effect. It really comes down to whether you want to encourage or discourage the use of the infrastructure.

by DC-3 5y ago

triska 5y ago

This phenomenon is known as the Jevons paradox, named after British logician, economist and statistician William Stanley Jevons: https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox

dalbasal 5y ago
Traffic/travel is a relatively special case though... We have a near unlimited ability to consume transport. If you could get to Japan in 20m, I would probably pop over for lunch right now or Vladivostok for a Sunday stroll. As transport improves, people work/shop/etc further from home. Commuting range is measured in time, not kms. So, capacity (eg traffic) tends to be the balancing force. That's more than the typical Jevons Paradox, I think.
- Tomte 5y ago
  For traffic you've got the even more interesting Braess's Paradox: https://en.wikipedia.org/wiki/Braess%27s_paradox https://en.wikipedia.org/wiki/Braess%27s_paradox
- maxsilver 5y ago
  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.
- GekkePrutser 5y ago
  This is true. If I could go to New Zealand for a weekend break in 20 minutes for cheap I'd be there every weekend..

martingoodson 5y ago

This is called ‘induced demand’. Surprisingly, the opposite happens when you remove road capacity - which is called ‘traffic evaporation’. It’s why taking road space from cars and reallocating it to bicycles is often more successful than predicted: https://nacto.org/docs/usdg/disappearing_traffic_cairns.pdf https://nacto.org/docs/usdg/disappearing_traffic_cairns.pdf

kqr 5y ago
Removing capacity from infrastructure is a solution that works when you want to discourage use of that infrastructure. If that's not the case, I only know of one other solution: charge directly for usage. That way you can set the price such that demand stays at a high level, but at one supported by maximum available capacity. If someone knows of a different solution, I'd like to know -- I have an induced demand problem in a type of infrastructure that I would like to operate at high capacity, and charging for it would be unconventional to the point of making it hard to find support for that solution.
- goodpoint 5y ago
  Charging money for access to transportation is very politically biased: people with low or no income are effectively denied transportation while people with high income are not discouraged. This is how slums are created. > If someone knows of a different solution, I'd like to know Some cities have areas that allow unlimited access to locals and deliveries and limited access to others (X times per year)
  - kqr 5y ago
    Yes, that's a problem. I've debated with myself over what would be a fair division of "limited access" in my case but not arrived at a satisfactory solution. Anything I can think of will devolve into an inefficient, sucky, inofficial market. (This is why I'm contemplating an efficient, less sucky, official market in the first place.) To be clear: the infrastructure I'm working on isn't transport, but it'd still be odd to only allow paying users. I was thinking two similar copies of this piece infrastructure, where one is priced to avoid congestion, and the other will be as congested as induced demand allows. I'd like the discussion to stay general because I suspect any solutions will be reusable.

atatatat 5y ago

In a city, yes. In a suburb, the solution isn't anything except building more and better roads. People aren't bicycling 10-15 miles to the grocery. They should be, but, that's a different societal problem.

oscardssmith 5y ago
In suburbs, we shouldn't have grocery stores be that far from people.
- OwlsParlay 5y ago
  Welcome to American zoning laws, sadly.
adamjb 5y ago
...are there really places in the US that are considered suburbs where the nearest place to get groceries is 10-15 miles away? That's appalling.
- other_herbert 5y ago
  I think most people would call that “the middle of nowhere” or out in the boonies... or it could be a new area that is growing.. 15 miles from groceries is too far to be called a suburb
  - masklinn 5y ago
    > I think most people would call that “the middle of nowhere” or out in the boonies... Not in the US. In the US "in the middle of nowhere" is grocery runs of 50+ miles. 15 miles is a "far out" suburbian hellscape e.g. https://i1.wp.com/cdn-images-1.medium.com/max/1080/1*AEfVhyvwGyqDmnZcAQfIGg.png?resize=398%2C264&ssl=1 https://i1.wp.com/cdn-images-1.medium.com/max/1080/1*AEfVhyv... or https://bostonglobe-prod.cdn.arcpublishing.com/resizer/h2N-h_4kbaMMps_4ou05IwXb6tM=/1024x0/arc-anglerfish-arc2-prod-bostonglobe.s3.amazonaws.com/public/Z4IGXQBGAII6HALMQUI2U2GARA.jpg https://bostonglobe-prod.cdn.arcpublishing.com/resizer/h2N-h...

choward 5y ago

It also encourages people to live further from where they work which also adds to traffic.

Wowfunhappy 5y ago

Of course, it does also mean more people are able to use the road (or canal). So it’s not a complete loss, even if it doesn’t have the intended effect. It really comes down to whether you want to encourage or discourage the use of the infrastructure.