4 ms·

Just like adding a lane doesn't improve traffic much because more people use the road

by eli 10y ago

nitrogen 10y ago
That claim is frequently used on HN to justify anti-driving policies, but the economic cost/benefit inside and outside the affected area is never considered. If you only focus on one metric (traffic density), you miss the bigger picture.
- sandworm101 10y ago
  Note that those making such arguments rarely extend them to bike lanes. If cutting lanes really reduces unneeded trips, that principal should apply to all modes of transport. Closing a subway station would certainly reduce the foot traffic cluttering up nearby sidewalks. Those people will work from home instead.
  - galdosdi 10y ago
    Your rhetorical question has an obvious answer, which I'll illustrate with evidence: I live in Manhattan, the USA's most crowded place in terms of bikes and pedestrians. Yet, we are not anywhere near capacity for bikes and pedestrians, anywhere, anytime. For cars, we are at/over capacity pretty much all the time during the day. Why is obvious -- cars are way bigger. Duh. Cars are just very space-ineffecient -- the space consumed by one car could service many times more transit riders, pedestrians, cyclists. Getting people to switch from car to anything else multiples manyfold the number of people we can service, which is a good thing. Getting people to switch from anything else, on the other hand, doesn't do much good. Even if we did reach sidewalk capacity somewhere, it would make sense to just convert one car lane into additional sidewalk, since a lane can fit at least 10x as many people if they're walking versus driving.
    - oftenwrong 10y ago
      Look at what Manhattan would need to become if every commuter drove a car in: https://mtayloranalysis.wordpress.com/2014/12/09/an-auto-oriented-manhattan/ https://mtayloranalysis.wordpress.com/2014/12/09/an-auto-ori...
      - galdosdi 10y ago
        Holy !@#$%! Yeah, exactly. Very nice visualization of how space-inefficient car transport is.
    - maxsilver 10y ago
      > I live in Manhattan, the USA's most crowded place in terms of bikes and pedestrians. Yet, we are not anywhere near capacity for bikes and pedestrians, anywhere, anytime. This is not true. From the NY Times -> "New York’s Sidewalks Are So Packed, Pedestrians Are Taking to the Streets" https://www.nytimes.com/2016/07/01/nyregion/new-york-city-overcrowded-sidewalks.html https://www.nytimes.com/2016/07/01/nyregion/new-york-city-ov...
      - galdosdi 10y ago
        That's unfairly using a different standard of congestion for pedestrians as for motorists. The kind of congestion midtown manhattan experiences for pedestrians is comparable to stop-and-go-but-moving car traffic. A bit unpleasant but there is still capacity. There's wasted capacity in the streets right now so pedestrians will overflow there, yeah, but if there was a fence, we could still increase the pedestrian density a good bit before reaching capacity. In other words, it's more comparable to stop-and-go averaging 15mph car traffic - uncomfortable, but still plenty of capacity left. It's not comparable to what we actually observe in car traffic at rush hour often -- mostly stopped, barely inching occasionally, averaging well under 5mph. When an event like a protest happens, THEN you actually see what true full-to-capacity looks like, and you realize that the day-to-day, while crowded and uncomfortable, has a long way to go before getting to capacity. Outside of an event like a protest, I've NEVER been walking through midtown and felt unable to make any progress at all. Compare that to driving. Or to put it another way, even at the worst of pedestrian congestion, the pedestrian is still faster than the car, so there is obviously still room left to make it even slower.
- awjr 10y ago
  Well London removed two lanes of traffic and installed a 4m wide 20km protected cycle super highway. This has increased capacity of the road by 5-10%. It's reduced the motorised vehicle traffic flow, but overall has increased the number of people they are moving through the same space. If the only type of transport you support on a road is the car, then you are in a world of hurt. In the UK, the bigger picture is that abotu 70% of road journeys are under 8km. Given good safe cycle infrastructure and maybe an eBike, most people could switch out of cars.
  - sandworm101 10y ago
    The average age in my city is over 60. "Most people" arent going to be rollerblading to the clinic for thier blood tests. Not everyone is a fit and healthy millenial, nor will taking away thier cars and busses make them so.
    - upofadown 10y ago
      Over 60 people tend to not mind if their drive takes a bit longer. Over 60 people who are too old to drive tend to take the bus.
      - scythe 10y ago
        You and I have met very different "over 60 people".
    - icebraining 10y ago
      This is a self-fulfilling prophecy. Older people will absolutely use bikes if you have a good cycling culture and infrastructure. And the ones who can't will have fewer street lanes, but also much less traffic.
- mrfusion 10y ago
  I think it's one of the false lessons a generation learned from playing sim city. You always wanted to avoid roads in sim city.
- HillaryBriss 10y ago
  right. i agree. and the original post seems to make an unjustified leap at the end. after spending the entire article discussing how traffic congestion didn't increase, they say: ...its a strong sign that more modest changes to road systems really don’t have much impact on metropolitan prosperity. the amount of traffic congestion and the economic prosperity of the Atlanta region are not the same thing at all. where does the article support the notion that the economy was not hurt?
stale2002 10y ago
Well, but now people are gaining value by being able to make trips that they couldn't make before.
sandworm101 10y ago
Unless by more people using that road, perhaps a more direct route, the total number of miles travelled goes down. Then that increased local traffic is a net positive for the larger area.
maxsilver 10y ago
Just like adding housing doesn't improve costs, because more people will just move in. Just like adding fiber lines doesn't improve internet speeds, because more data will be moved around. Just like using renewable energy doesn't reduce pollution, because more people will just use renewable energy. --- Except, that's not true, that's not what happens. On roads, or any of these other situations. Induced demand is a small and rare situation only applicable when multiple other valuable alternatives exist with which to pull from. To slap that label onto any piece of infrastructure is simply not accurate.
- oftenwrong 10y ago
  Induced demand occurs when the price of using something is not dependent on demand. A road without a toll is a good example of this because the cost of using the road, relative to alternatives, is low. It's like a restaurant that gives out free food - why wouldn't you want to eat there? Forget other restaurants, and forget cooking at home. Free food! Except the line will likely be longer than at a restaurant that costs money. If you add a demand-priced toll to a road, and adjust the price to maintain a certain level of traffic flow, induced demand will not occur. If traffic is congested, raise the price. If traffic is flowing freely and sparsely, lower the price.
  - maxsilver 10y ago
    > It's like a restaurant that gives out free food - why wouldn't you want to eat there? Because I'm not hungry. A restaurant is a good example -- it does not induce demand, it services it. If lots of hungry people are around, a free restaurant will service them. And if hunger is a persistent issue, then yes, your restaurant might be packed and busy. But that's never an argument to tear down a restaurant! A restaurant does not create hunger, a restaurant does not cause hunger -- it solves hunger for some number of people. And making the restaurant free doesn't make that problem worse, it makes it better. Lots more people get fed, and almost no one is going to sit around and eat 20 lunches per day, even if it's free to do so. > If you add a demand-priced toll to a road, and adjust the price to maintain a certain level of traffic flow, induced demand will not occur. Sure it will, your just not measuring it. You've just "induced demand" on a bunch of other non-toll roads, that are all conveniently not this specific road, so your limited statistics of this road can artificially make your change look successful. 'Solving traffic' by tearing down roads, is roughly akin to 'curing diseases' by tearing down hospitals. It makes your stats look good, by making those statistics lie through omission.
deleted 10y ago
[deleted]

Just like adding a lane doesn't improve traffic much because more people use the road

by eli 10y ago

Just like adding a lane doesn't improve traffic much because more people use the road

That claim is frequently used on HN to justify anti-driving policies, but the economic cost/benefit inside and outside the affected area is never considered. If you only focus on one metric (traffic density), you miss the bigger picture.

sandworm101 10y ago
Note that those making such arguments rarely extend them to bike lanes. If cutting lanes really reduces unneeded trips, that principal should apply to all modes of transport. Closing a subway station would certainly reduce the foot traffic cluttering up nearby sidewalks. Those people will work from home instead.
- galdosdi 10y ago
  Your rhetorical question has an obvious answer, which I'll illustrate with evidence: I live in Manhattan, the USA's most crowded place in terms of bikes and pedestrians. Yet, we are not anywhere near capacity for bikes and pedestrians, anywhere, anytime. For cars, we are at/over capacity pretty much all the time during the day. Why is obvious -- cars are way bigger. Duh. Cars are just very space-ineffecient -- the space consumed by one car could service many times more transit riders, pedestrians, cyclists. Getting people to switch from car to anything else multiples manyfold the number of people we can service, which is a good thing. Getting people to switch from anything else, on the other hand, doesn't do much good. Even if we did reach sidewalk capacity somewhere, it would make sense to just convert one car lane into additional sidewalk, since a lane can fit at least 10x as many people if they're walking versus driving.
  - oftenwrong 10y ago
    Look at what Manhattan would need to become if every commuter drove a car in: https://mtayloranalysis.wordpress.com/2014/12/09/an-auto-oriented-manhattan/ https://mtayloranalysis.wordpress.com/2014/12/09/an-auto-ori...
    - galdosdi 10y ago
      Holy !@#$%! Yeah, exactly. Very nice visualization of how space-inefficient car transport is.
  - maxsilver 10y ago
    > I live in Manhattan, the USA's most crowded place in terms of bikes and pedestrians. Yet, we are not anywhere near capacity for bikes and pedestrians, anywhere, anytime. This is not true. From the NY Times -> "New York’s Sidewalks Are So Packed, Pedestrians Are Taking to the Streets" https://www.nytimes.com/2016/07/01/nyregion/new-york-city-overcrowded-sidewalks.html https://www.nytimes.com/2016/07/01/nyregion/new-york-city-ov...
    - galdosdi 10y ago
      That's unfairly using a different standard of congestion for pedestrians as for motorists. The kind of congestion midtown manhattan experiences for pedestrians is comparable to stop-and-go-but-moving car traffic. A bit unpleasant but there is still capacity. There's wasted capacity in the streets right now so pedestrians will overflow there, yeah, but if there was a fence, we could still increase the pedestrian density a good bit before reaching capacity. In other words, it's more comparable to stop-and-go averaging 15mph car traffic - uncomfortable, but still plenty of capacity left. It's not comparable to what we actually observe in car traffic at rush hour often -- mostly stopped, barely inching occasionally, averaging well under 5mph. When an event like a protest happens, THEN you actually see what true full-to-capacity looks like, and you realize that the day-to-day, while crowded and uncomfortable, has a long way to go before getting to capacity. Outside of an event like a protest, I've NEVER been walking through midtown and felt unable to make any progress at all. Compare that to driving. Or to put it another way, even at the worst of pedestrian congestion, the pedestrian is still faster than the car, so there is obviously still room left to make it even slower.
awjr 10y ago
Well London removed two lanes of traffic and installed a 4m wide 20km protected cycle super highway. This has increased capacity of the road by 5-10%. It's reduced the motorised vehicle traffic flow, but overall has increased the number of people they are moving through the same space. If the only type of transport you support on a road is the car, then you are in a world of hurt. In the UK, the bigger picture is that abotu 70% of road journeys are under 8km. Given good safe cycle infrastructure and maybe an eBike, most people could switch out of cars.
- sandworm101 10y ago
  The average age in my city is over 60. "Most people" arent going to be rollerblading to the clinic for thier blood tests. Not everyone is a fit and healthy millenial, nor will taking away thier cars and busses make them so.
  - upofadown 10y ago
    Over 60 people tend to not mind if their drive takes a bit longer. Over 60 people who are too old to drive tend to take the bus.
    - scythe 10y ago
      You and I have met very different "over 60 people".
  - icebraining 10y ago
    This is a self-fulfilling prophecy. Older people will absolutely use bikes if you have a good cycling culture and infrastructure. And the ones who can't will have fewer street lanes, but also much less traffic.
mrfusion 10y ago
I think it's one of the false lessons a generation learned from playing sim city. You always wanted to avoid roads in sim city.
HillaryBriss 10y ago
right. i agree. and the original post seems to make an unjustified leap at the end. after spending the entire article discussing how traffic congestion didn't increase, they say: ...its a strong sign that more modest changes to road systems really don’t have much impact on metropolitan prosperity. the amount of traffic congestion and the economic prosperity of the Atlanta region are not the same thing at all. where does the article support the notion that the economy was not hurt?

stale2002 10y ago

Well, but now people are gaining value by being able to make trips that they couldn't make before.

sandworm101 10y ago

Unless by more people using that road, perhaps a more direct route, the total number of miles travelled goes down. Then that increased local traffic is a net positive for the larger area.

maxsilver 10y ago

Just like adding housing doesn't improve costs, because more people will just move in. Just like adding fiber lines doesn't improve internet speeds, because more data will be moved around. Just like using renewable energy doesn't reduce pollution, because more people will just use renewable energy. --- Except, that's not true, that's not what happens. On roads, or any of these other situations. Induced demand is a small and rare situation only applicable when multiple other valuable alternatives exist with which to pull from. To slap that label onto any piece of infrastructure is simply not accurate.

oftenwrong 10y ago
Induced demand occurs when the price of using something is not dependent on demand. A road without a toll is a good example of this because the cost of using the road, relative to alternatives, is low. It's like a restaurant that gives out free food - why wouldn't you want to eat there? Forget other restaurants, and forget cooking at home. Free food! Except the line will likely be longer than at a restaurant that costs money. If you add a demand-priced toll to a road, and adjust the price to maintain a certain level of traffic flow, induced demand will not occur. If traffic is congested, raise the price. If traffic is flowing freely and sparsely, lower the price.
- maxsilver 10y ago
  > It's like a restaurant that gives out free food - why wouldn't you want to eat there? Because I'm not hungry. A restaurant is a good example -- it does not induce demand, it services it. If lots of hungry people are around, a free restaurant will service them. And if hunger is a persistent issue, then yes, your restaurant might be packed and busy. But that's never an argument to tear down a restaurant! A restaurant does not create hunger, a restaurant does not cause hunger -- it solves hunger for some number of people. And making the restaurant free doesn't make that problem worse, it makes it better. Lots more people get fed, and almost no one is going to sit around and eat 20 lunches per day, even if it's free to do so. > If you add a demand-priced toll to a road, and adjust the price to maintain a certain level of traffic flow, induced demand will not occur. Sure it will, your just not measuring it. You've just "induced demand" on a bunch of other non-toll roads, that are all conveniently not this specific road, so your limited statistics of this road can artificially make your change look successful. 'Solving traffic' by tearing down roads, is roughly akin to 'curing diseases' by tearing down hospitals. It makes your stats look good, by making those statistics lie through omission.

deleted 10y ago

[deleted]