7 ms·

A similar concept is that of induced demand [0]. When cities expand the number of highway lanes, for example, sometimes they find that traffic and congestion ac

A similar concept is that of induced demand [0]. When cities expand the number of highway lanes, for example, sometimes they find that traffic and congestion actually increase. 0: https://en.wikipedia.org/wiki/Induced_demand https://en.wikipedia.org/wiki/Induced_demand

CalRobert 3y ago
Indeed, it's used as a great example of Jevon's Paradox at https://youtu.be/pCzCJzwrB_c?si=N8PgXPv3fCEDvdfN&t=103 https://youtu.be/pCzCJzwrB_c?si=N8PgXPv3fCEDvdfN&t=103
autoexec 3y ago
The way induced demand is framed sometimes as an argument for not expanding busy roads really bugs me. It's not that adding a new lane to a busy road suddenly creates the demand to drive on it. The "demand" already exists and simply isn't being met by the inadequate infrastructure. If there's an aquarium at the end of a busy road, and I'm extremely offended by the sight of fish, no amount of added lanes is going to "induce" me to want to get up on a Saturday and drive to the aquarium. However, if there's a opera house at the end of a busy road and I love the opera and want to go every weekend, inadequate infrastructure can make the experience driving there painful enough that I'll just stay home, but my desire to go there hasn't changed. I'd still love to see the opera and adding enough new lanes will mean I'm able to go. If congestion increases immediately after new lanes for traffic are added it's probably because the existing demand to travel down that particular road has been being ignored for way too long. As long as you're a fan of allowing people to go to the places they want to visit, then adding new lanes of traffic is a really good idea even when it results in more cars on the road. The goal of the larger road should be to allow more people to get to where they want to be, not to reduce the number of cars using it.
- MalcolmDwyer 3y ago
  No, the new demand is induced. Among the many things people consider when buying a house or choosing a new place to rent, is the commute time to wherever they might need to go. A suburb with an hour commute from the job is low on most people's list. Here comes a new highway, or new highway lanes, and now it's only 30 minutes. Great, let's move there... along with 20,000 other people and within a couple years the commute is back to an hour.
  - autoexec 3y ago
    Busy roads are busy because of existing demand, new demand can be created by new roads/lanes and cause the expanded roads to become busier, but that's a really good thing not a bad one. New roads should be planned/expanded with that in mind because the moment existing demand starts to exceed what the current roads can handle it becomes time to build new roads or expand existing ones again. Allowing outdated and inadequate infrastructure to make people miserable and hinder a thriving local economy is a terrible idea. Improving and adapting our roadways to meet the needs of a growing community is exactly what we want cities to do. We shouldn't use induced demand as an excuse to neglect that responsibility, we just have to understand the effect so that we can plan for it.
    - firedaemon 3y ago
      Mostly I think the idea of induced demand should encourage us to increase the availability of transportation in “novel” ways as opposed to just adding more road. You can add more road forever and just get more traffic. If instead you add rail, say, you satisfy demand and avoid a concrete highway hellscape.
      - autoexec 3y ago
        I 100% agree. Too often though it's used as an excuse to not update roadways in places where there are zero efforts being made to introduce new public transportation. It's also worth noting that induced demand exists even for public transportation systems. A single rail line can solve the bandwidth problem for a longer time than a new lane on a highway, but if growth continues you'll still end up needing to add new trains and rail lines or add additional modes of mass transportation. Induced demand is never a reason to leave the problem of bad infrastructure unaddressed, it's just something we have to take into account as we try to improve things.
        NeoTar 3y ago
        There were suggestions (pre-Covid) that the Elizabeth line, which increased east-west capacity in London by some ridiculous figure (over 50% if I recall correctly) could be saturated by induced demand (or if you prefer the realisation of suppressed demand) within six months of opening.
- pixl97 3y ago
  It is more complicated than this... There is a trade off while going to popular places. An Opera house is a big attraction that you tend to get tickets for so you're willing to spend some extra time in traffic for it... Now lower the time in traffic and suddenly you're deciding to get a meal a nice restaurant in the area too. But people not going to the Opera will also go to that nice restaurant that the travel cost has lowered. And because this is the US and cars are king, each one of us is taking our own set of 4 wheeled transportation. And that transportation needs to park somewhere. And this is where things tend to fall apart quickly. At the end of the day it would be far cheaper and easier for everyone if we were taking public/mass transportation to these busy spots, but because we don't design our lives around this it becomes impossible.
  - autoexec 3y ago
    It's also true that once a city finally stops ignoring the inadequate bandwidth of an extremely busy road and expands it, new businesses and attractions may want to be built along that more pleasant road leading to more people wanting to take the road. I agree entirely that a great public transportation system is a much better solution, but for places that don't have one and aren't going to create one, insisting that induced demand makes expanding roads inappropriate is just... wrong. Ultimately, if falls on cities to provide people with a way to get to where they want to be and leaving bottlenecks in place makes people miserable and stifles the local economy.
    - pixl97 3y ago
      > and stifles the local economy. Oh no, we're going going to stifle the local economy for billions of dollars, and all we have to do is take on 10s to 100s of billion of dollars of debt to avoid it... This is just turning into a hedonistic treadmill of turning more and more of your space into transportation infrastructure by means of debt.
      - autoexec 3y ago
        It's hardly hedonistic to want to leave your house and investing in transportation infrastructure should pay for itself.
- jihadjihad 3y ago
  Right, and I think what you're getting at is that there is a distinction between the generated demand that the new lanes induce, and the latent demand which was already present before the new lanes were added but went unsatisfied. Adding new lanes to the road allows that latent, pent-up demand to be satisfied--the induced/generated demand is the mechanism of that satisfaction.
- renewiltord 3y ago
  The "induced demand" isn't a bad thing. It means more people are getting some utility out of them. The reason why folks bring up "induced demand" is when someone says that roadways should be expanded to reduce commute times. Commute times will often not be reduced: only that more people will be able to commute. Usually the solution then is not to optimize for road transportation. After a threshold, it makes sense to switch to a more efficient use of land. Essentially, if you added two more lanes to 101, it's still going to take you as long to get to Palo Alto. Roads are very good things. But they are very costly land-use-wise. So ideally you have lots of roads as a discovery mechanism and then place high-frequency fast transit along the most well-used. Most of America is in regulatory hell, though, so transit is slow and low-frequency, so the road may actually be net better.
- notatoad 3y ago
  >The "demand" already exists and simply isn't being met by the inadequate infrastructure. the induced demand argument isn't simply that we should never build transportation infrastrucutre, it's that adding a lane to an existing road is a bad way to meet that demand because the traffic that one lane can carry is insufficient to exceed the demand that one lane will induce. yes, the road expansion will be "successful" in that people will use it. but if it was pitched as a way to improve travel times, reduce congestion, or improve safety, that will probably be a failure. if you're not going to the opera because the road is too busy, and the added lane releases that unmet demand, the road will still be just as busy as before and you still won't get to the opera. everybody else is doing the same math as you, and deciding that if the road isn't too busy they're going to drive. and so the road is always too busy.
- ViewTrick1002 3y ago
  To reduce congestion you need to speed up and expand the slowest alternative, public transport. That is the only proven method to reduce congestion. The peak demand for car travel is way beyond the infrastructure which is possible to construct and maintain. More info: https://youtu.be/RQY6WGOoYis https://youtu.be/RQY6WGOoYis
pixl97 3y ago
I see this happen with cloud services all the time... Customer has on prem services that they do X operations with, we'll say 10,000 daily as an example. They look at the metrics and moving to cloud for that many operations would be cheaper. But very soon after moving to the cloud and an expandable infrastructure, operational costs explode. Suddenly they are not doing this 10k times a day, they are doing it 20 or 30k times a day. Whereas before before kicking off whatever job they were doing they were careful to ensure it was important and cleaning up mistakes in scripts doing while 1=1 loops because it had a measurable impact, after the backpressure disappeared, they'd do this operation without thinking about the costs.

CalRobert 3y ago

Indeed, it's used as a great example of Jevon's Paradox at https://youtu.be/pCzCJzwrB_c?si=N8PgXPv3fCEDvdfN&t=103 https://youtu.be/pCzCJzwrB_c?si=N8PgXPv3fCEDvdfN&t=103

autoexec 3y ago

The way induced demand is framed sometimes as an argument for not expanding busy roads really bugs me. It's not that adding a new lane to a busy road suddenly creates the demand to drive on it. The "demand" already exists and simply isn't being met by the inadequate infrastructure. If there's an aquarium at the end of a busy road, and I'm extremely offended by the sight of fish, no amount of added lanes is going to "induce" me to want to get up on a Saturday and drive to the aquarium. However, if there's a opera house at the end of a busy road and I love the opera and want to go every weekend, inadequate infrastructure can make the experience driving there painful enough that I'll just stay home, but my desire to go there hasn't changed. I'd still love to see the opera and adding enough new lanes will mean I'm able to go. If congestion increases immediately after new lanes for traffic are added it's probably because the existing demand to travel down that particular road has been being ignored for way too long. As long as you're a fan of allowing people to go to the places they want to visit, then adding new lanes of traffic is a really good idea even when it results in more cars on the road. The goal of the larger road should be to allow more people to get to where they want to be, not to reduce the number of cars using it.

MalcolmDwyer 3y ago
No, the new demand is induced. Among the many things people consider when buying a house or choosing a new place to rent, is the commute time to wherever they might need to go. A suburb with an hour commute from the job is low on most people's list. Here comes a new highway, or new highway lanes, and now it's only 30 minutes. Great, let's move there... along with 20,000 other people and within a couple years the commute is back to an hour.
- autoexec 3y ago
  Busy roads are busy because of existing demand, new demand can be created by new roads/lanes and cause the expanded roads to become busier, but that's a really good thing not a bad one. New roads should be planned/expanded with that in mind because the moment existing demand starts to exceed what the current roads can handle it becomes time to build new roads or expand existing ones again. Allowing outdated and inadequate infrastructure to make people miserable and hinder a thriving local economy is a terrible idea. Improving and adapting our roadways to meet the needs of a growing community is exactly what we want cities to do. We shouldn't use induced demand as an excuse to neglect that responsibility, we just have to understand the effect so that we can plan for it.
  - firedaemon 3y ago
    Mostly I think the idea of induced demand should encourage us to increase the availability of transportation in “novel” ways as opposed to just adding more road. You can add more road forever and just get more traffic. If instead you add rail, say, you satisfy demand and avoid a concrete highway hellscape.
    - autoexec 3y ago
      I 100% agree. Too often though it's used as an excuse to not update roadways in places where there are zero efforts being made to introduce new public transportation. It's also worth noting that induced demand exists even for public transportation systems. A single rail line can solve the bandwidth problem for a longer time than a new lane on a highway, but if growth continues you'll still end up needing to add new trains and rail lines or add additional modes of mass transportation. Induced demand is never a reason to leave the problem of bad infrastructure unaddressed, it's just something we have to take into account as we try to improve things.
      - NeoTar 3y ago
        There were suggestions (pre-Covid) that the Elizabeth line, which increased east-west capacity in London by some ridiculous figure (over 50% if I recall correctly) could be saturated by induced demand (or if you prefer the realisation of suppressed demand) within six months of opening.
pixl97 3y ago
It is more complicated than this... There is a trade off while going to popular places. An Opera house is a big attraction that you tend to get tickets for so you're willing to spend some extra time in traffic for it... Now lower the time in traffic and suddenly you're deciding to get a meal a nice restaurant in the area too. But people not going to the Opera will also go to that nice restaurant that the travel cost has lowered. And because this is the US and cars are king, each one of us is taking our own set of 4 wheeled transportation. And that transportation needs to park somewhere. And this is where things tend to fall apart quickly. At the end of the day it would be far cheaper and easier for everyone if we were taking public/mass transportation to these busy spots, but because we don't design our lives around this it becomes impossible.
- autoexec 3y ago
  It's also true that once a city finally stops ignoring the inadequate bandwidth of an extremely busy road and expands it, new businesses and attractions may want to be built along that more pleasant road leading to more people wanting to take the road. I agree entirely that a great public transportation system is a much better solution, but for places that don't have one and aren't going to create one, insisting that induced demand makes expanding roads inappropriate is just... wrong. Ultimately, if falls on cities to provide people with a way to get to where they want to be and leaving bottlenecks in place makes people miserable and stifles the local economy.
  - pixl97 3y ago
    > and stifles the local economy. Oh no, we're going going to stifle the local economy for billions of dollars, and all we have to do is take on 10s to 100s of billion of dollars of debt to avoid it... This is just turning into a hedonistic treadmill of turning more and more of your space into transportation infrastructure by means of debt.
    - autoexec 3y ago
      It's hardly hedonistic to want to leave your house and investing in transportation infrastructure should pay for itself.
jihadjihad 3y ago
Right, and I think what you're getting at is that there is a distinction between the generated demand that the new lanes induce, and the latent demand which was already present before the new lanes were added but went unsatisfied. Adding new lanes to the road allows that latent, pent-up demand to be satisfied--the induced/generated demand is the mechanism of that satisfaction.
renewiltord 3y ago
The "induced demand" isn't a bad thing. It means more people are getting some utility out of them. The reason why folks bring up "induced demand" is when someone says that roadways should be expanded to reduce commute times. Commute times will often not be reduced: only that more people will be able to commute. Usually the solution then is not to optimize for road transportation. After a threshold, it makes sense to switch to a more efficient use of land. Essentially, if you added two more lanes to 101, it's still going to take you as long to get to Palo Alto. Roads are very good things. But they are very costly land-use-wise. So ideally you have lots of roads as a discovery mechanism and then place high-frequency fast transit along the most well-used. Most of America is in regulatory hell, though, so transit is slow and low-frequency, so the road may actually be net better.
notatoad 3y ago
>The "demand" already exists and simply isn't being met by the inadequate infrastructure. the induced demand argument isn't simply that we should never build transportation infrastrucutre, it's that adding a lane to an existing road is a bad way to meet that demand because the traffic that one lane can carry is insufficient to exceed the demand that one lane will induce. yes, the road expansion will be "successful" in that people will use it. but if it was pitched as a way to improve travel times, reduce congestion, or improve safety, that will probably be a failure. if you're not going to the opera because the road is too busy, and the added lane releases that unmet demand, the road will still be just as busy as before and you still won't get to the opera. everybody else is doing the same math as you, and deciding that if the road isn't too busy they're going to drive. and so the road is always too busy.
ViewTrick1002 3y ago
To reduce congestion you need to speed up and expand the slowest alternative, public transport. That is the only proven method to reduce congestion. The peak demand for car travel is way beyond the infrastructure which is possible to construct and maintain. More info: https://youtu.be/RQY6WGOoYis https://youtu.be/RQY6WGOoYis

pixl97 3y ago

I see this happen with cloud services all the time... Customer has on prem services that they do X operations with, we'll say 10,000 daily as an example. They look at the metrics and moving to cloud for that many operations would be cheaper. But very soon after moving to the cloud and an expandable infrastructure, operational costs explode. Suddenly they are not doing this 10k times a day, they are doing it 20 or 30k times a day. Whereas before before kicking off whatever job they were doing they were careful to ensure it was important and cleaning up mistakes in scripts doing while 1=1 loops because it had a measurable impact, after the backpressure disappeared, they'd do this operation without thinking about the costs.