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The idea that induced demand entirely compensates for new road capacity is ridiculous on its face. This would only be nearly the case if the road infrastructure

The idea that induced demand entirely compensates for new road capacity is ridiculous on its face. This would only be nearly the case if the road infrastructure is vastly behind what's needed. Even then, much of the newly accommodated traffic will be of economic benefit. Consider that the theory states that traffic is unchanged because people will be incentivized to drive more because of less traffic. This is self contradictory - there can't be both less traffic and the same traffic.

pfortuny 11y ago
Inertia makes things react late to forces. Same here. The article clearly states that the new capacity is essentially filled in the long (10 year range) term, not the short one.
- skellington 11y ago
  Wow, what an illuminating study. If you build roads and the population continues to grow and/or pent up demand is release, those roads will eventually/immediately clog up. Obviously people use roads until the equilibrium of pain is met (like any economic decision). But, there is a point where you can supply so much capacity that there won't be traffic. It's a lie to say that no amount of capacity can overwhelm all forms of demand. The only real question is how much road would it take to fully satisfy demand and what would that cost vs the alternatives. (Ignoring pollution issues)
  - Majestic121 11y ago
    I don't see any good reason to ignore pollution when looking for the best solution.
  - lhopki01 11y ago
    And what is that point? More roads mean less living area which means more roads to get out to where there is living area. A poorly designed response to a problem makes the problem even worse. There are better ways of dealing with pent up demand for movement than to build more roads. Ones that are more efficient of resources, that are better for the environment and that provide a better quality of life for everyone.
revelation 11y ago
Nobody is saying that. The problem with induced demand for roads is induced demand for personal cars. Transport is a zero-sum game, someone who takes the personal car to work is someone not taking the train. As countless studies attest, this is not of economic (or personal) benefit. It locks people into a life-long dependency on cars with the terrible health outcomes for them personally and the humongous cost of human life in traffic deaths every year.
- dsfyu404ed 11y ago
  "the terrible health outcomes for them personally" Cite this, I dare you. edit: the part I'm not buying is the combination of "terrible" and "personal" It matters little whether you're sitting on your but for 45min in a car or on a bus, you're still not getting exercise. That's not really "terrible" as it's something that can easily be counteracted unlike (for example) working in a loud environment for 45min twice per day without hearing protection. The "terrible" stuff (accidents) isn't really personal because it only comes into play on a statistical level (seeing as most people will never be seriously injured in a vehicle accident)
  - andys627 11y ago
    http://jpubhealth.oxfordjournals.org/content/33/2/160.full http://jpubhealth.oxfordjournals.org/content/33/2/160.full this cites about 50 more that could be listed
  - mikerichards 11y ago
    It's funny how people will make things up to satisfy the HN anti-car hive mind. Sorry people, you're living in a bubble. The vast, vast, VAST majority of people don't hate cars like the HN collective does.
    - distances 11y ago
      Many countries in Europe have a clear generational change ongoing: young people are much less likely to get a car or a driver's license. I would expect HN just to reflect this general trend.
dsfyu404ed 11y ago
For high demand times of day the infrastructure is vastly behind what's needed...
- maxerickson 11y ago
  Especially if you take "needed" to mean the amount of infrastructure that would be utilized in a particular place if it existed. Much of the point of public planning is that in practice that definition of need isn't one that really creates fantastic outcomes.
rplst8 11y ago
I think in some major metro areas, the road capacity is vastly behind what is needed. My commute is is 26 miles of limited access highway that occurs at nearly 1/3 to 1/2 of the posted speed limit. The only reason there is induced demand is that the infrastructure is too small to support the way our cities and metro areas have evolved. Maybe the way they have evolved is a product of the Eisenhower Interstate highway system, but we're already invested in that infrastructure. It would take an inordinate amount of money, resources, and effort to relocate and redesign our cities than to just build the correct size (and number) of highways to support the population. In addition - one thing that it seems highway planners rarely plan correctly for is growth. The population of the Washington DC metro area has grown from about 3 million in 1980 to over 6 million currently. Many of the highways are nearly the same size over that span.
- angdis 11y ago
  DC actually did plan for growth when they build the metro. Everyday it transports a staggering number of people which would be intractable for ANY highway system if these same people drove. What they failed to account for, however, is the growth of exburbs like Ashburn VA and other places even further out like Frederick MD. These remote places are built by developers who literally put ZERO thought into infrastructure and what will happen to traffic and many other things when thousands of well-paid people move into their McMansions in the middle of nowhere. They just buy up farmland from farmers who want to retire, sell a fake dream of idyllic rural living, plop down a bunch of cookie-cutter houses, then take the money and do all over again somewhere else. People have been finally getting wise to this anti-pattern (it was known in Maryland since the 90's) and the citylab article is an example.
  - rplst8 11y ago
    The DC Metro has a daily ridership of about 700,000 trips. This is nothing to sneeze at, and it is impressive. However, I'm not positive how they calculate a trip, but my guess is that it's a card swipe entry and exit. Most people are traveling to and from work, so that is likely half that number in unique people. So say 350,000 - 400,000 a day. On the other hand, I-270 through Maryland sees about 200,000 cars daily. That's one highway - with at least some cars carrying more than 1 person. Interstates 66 and 95, US route 50, MD route 295, and VA route 267 all carry similar amounts of traffic. And lets not forget the other minor routes and streets that carry additional traffic. Your assertion that it "would be intractable for ANY highway system" to handle this is absurd - it already does. While I too find some scorn for the McMansion culture, it is not really a local developers job or role to plan for medium to long distance infrastructure. I don't think it would even be legally possible for a private entity to take on a highway project that crossed multiple counties and/or states without a massive amount of support from local and state governments. Also, I wouldn't call suburban and rural development an anti-pattern. Unless you want the cities to be double the density they already are, some people are going to have to live in the suburbs and rural parts of the country.

pfortuny 11y ago

Inertia makes things react late to forces. Same here. The article clearly states that the new capacity is essentially filled in the long (10 year range) term, not the short one.

skellington 11y ago
Wow, what an illuminating study. If you build roads and the population continues to grow and/or pent up demand is release, those roads will eventually/immediately clog up. Obviously people use roads until the equilibrium of pain is met (like any economic decision). But, there is a point where you can supply so much capacity that there won't be traffic. It's a lie to say that no amount of capacity can overwhelm all forms of demand. The only real question is how much road would it take to fully satisfy demand and what would that cost vs the alternatives. (Ignoring pollution issues)
- Majestic121 11y ago
  I don't see any good reason to ignore pollution when looking for the best solution.
- lhopki01 11y ago
  And what is that point? More roads mean less living area which means more roads to get out to where there is living area. A poorly designed response to a problem makes the problem even worse. There are better ways of dealing with pent up demand for movement than to build more roads. Ones that are more efficient of resources, that are better for the environment and that provide a better quality of life for everyone.

revelation 11y ago

Nobody is saying that. The problem with induced demand for roads is induced demand for personal cars. Transport is a zero-sum game, someone who takes the personal car to work is someone not taking the train. As countless studies attest, this is not of economic (or personal) benefit. It locks people into a life-long dependency on cars with the terrible health outcomes for them personally and the humongous cost of human life in traffic deaths every year.

dsfyu404ed 11y ago
"the terrible health outcomes for them personally" Cite this, I dare you. edit: the part I'm not buying is the combination of "terrible" and "personal" It matters little whether you're sitting on your but for 45min in a car or on a bus, you're still not getting exercise. That's not really "terrible" as it's something that can easily be counteracted unlike (for example) working in a loud environment for 45min twice per day without hearing protection. The "terrible" stuff (accidents) isn't really personal because it only comes into play on a statistical level (seeing as most people will never be seriously injured in a vehicle accident)
- andys627 11y ago
  http://jpubhealth.oxfordjournals.org/content/33/2/160.full http://jpubhealth.oxfordjournals.org/content/33/2/160.full this cites about 50 more that could be listed
- mikerichards 11y ago
  It's funny how people will make things up to satisfy the HN anti-car hive mind. Sorry people, you're living in a bubble. The vast, vast, VAST majority of people don't hate cars like the HN collective does.
  - distances 11y ago
    Many countries in Europe have a clear generational change ongoing: young people are much less likely to get a car or a driver's license. I would expect HN just to reflect this general trend.

dsfyu404ed 11y ago

For high demand times of day the infrastructure is vastly behind what's needed...

maxerickson 11y ago
Especially if you take "needed" to mean the amount of infrastructure that would be utilized in a particular place if it existed. Much of the point of public planning is that in practice that definition of need isn't one that really creates fantastic outcomes.

rplst8 11y ago

I think in some major metro areas, the road capacity is vastly behind what is needed. My commute is is 26 miles of limited access highway that occurs at nearly 1/3 to 1/2 of the posted speed limit. The only reason there is induced demand is that the infrastructure is too small to support the way our cities and metro areas have evolved. Maybe the way they have evolved is a product of the Eisenhower Interstate highway system, but we're already invested in that infrastructure. It would take an inordinate amount of money, resources, and effort to relocate and redesign our cities than to just build the correct size (and number) of highways to support the population. In addition - one thing that it seems highway planners rarely plan correctly for is growth. The population of the Washington DC metro area has grown from about 3 million in 1980 to over 6 million currently. Many of the highways are nearly the same size over that span.

angdis 11y ago
DC actually did plan for growth when they build the metro. Everyday it transports a staggering number of people which would be intractable for ANY highway system if these same people drove. What they failed to account for, however, is the growth of exburbs like Ashburn VA and other places even further out like Frederick MD. These remote places are built by developers who literally put ZERO thought into infrastructure and what will happen to traffic and many other things when thousands of well-paid people move into their McMansions in the middle of nowhere. They just buy up farmland from farmers who want to retire, sell a fake dream of idyllic rural living, plop down a bunch of cookie-cutter houses, then take the money and do all over again somewhere else. People have been finally getting wise to this anti-pattern (it was known in Maryland since the 90's) and the citylab article is an example.
- rplst8 11y ago
  The DC Metro has a daily ridership of about 700,000 trips. This is nothing to sneeze at, and it is impressive. However, I'm not positive how they calculate a trip, but my guess is that it's a card swipe entry and exit. Most people are traveling to and from work, so that is likely half that number in unique people. So say 350,000 - 400,000 a day. On the other hand, I-270 through Maryland sees about 200,000 cars daily. That's one highway - with at least some cars carrying more than 1 person. Interstates 66 and 95, US route 50, MD route 295, and VA route 267 all carry similar amounts of traffic. And lets not forget the other minor routes and streets that carry additional traffic. Your assertion that it "would be intractable for ANY highway system" to handle this is absurd - it already does. While I too find some scorn for the McMansion culture, it is not really a local developers job or role to plan for medium to long distance infrastructure. I don't think it would even be legally possible for a private entity to take on a highway project that crossed multiple counties and/or states without a massive amount of support from local and state governments. Also, I wouldn't call suburban and rural development an anti-pattern. Unless you want the cities to be double the density they already are, some people are going to have to live in the suburbs and rural parts of the country.