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Overall I liked this article. It describes an interesting though simple core principle. I have three criticisms: 1. The article is scientific enough that using

Overall I liked this article. It describes an interesting though simple core principle. I have three criticisms: 1. The article is scientific enough that using "grew exponentially" in the colloquial sense of just "grew a lot" is grating. 2. The article gives the impression that Boston is an American city on a grid where elevated trains preceded subways and dominated the transportation system. In reality the core of the city was not at all a grid, subways came first, and subways have been more prevalent than elevated trains. 3. "the vaunted self-driving car, as imminent and yet illusory as nuclear fusion, will not transform the basic geometry of road capacity" This ignores the potential drastic reduction of space allocated for parking, including space that is already part of roadways.

human20190310 7y ago
I think "growing exponentially" is technically correct. Anything that grows at a rate proportional to its size is growing exponentially. The transportation innovations allowed cities to keep doing that, i.e. growing at X% per year instead of hitting some limit where population growth would force out-migration.
- brlewis 7y ago
  OK yes there's a reasonable use of the term early in the article that I overlooked. It was the "streetcars and bicycles" section where it grated on me.
blauditore 7y ago
> This ignores the potential drastic reduction of space allocated for parking How so? If you mean because of more car sharing, I don't think that's going to happen. Most people would still want their own car. If you mean because of being able to let the car park itself outside the city, or even drive home: That would drive up cost for the owner and reduce convenience (having to "order" it 30 minutes ahead of time). In addition, it would worsen congestion on streets due to cars moving more.
- cryptonector 7y ago
  I can imagine NYC with 1/10th the private cars and 4x the shared/rental/taxi cars, and traffic flowing much better than today owing to the additional bandwidth freed up by the 70-80% reduction in street-side parking space need. NYC residents just might accept the trade-off.
  - kiliantics 7y ago
    As an NYC resident, I would much prefer to just have 1/10th the private cars, twice the number of trains (or whatever is necessary), and a massive reduction in the number of cars sitting around unused, with the resulting extra space being converted to green space, pedestrian-only areas, and bike lanes. Self-driving cars and the infrastructure they necessitate would make NYC more hostile to people, not less.
    - vkou 7y ago
      As a non-NYC resident, I would love to see the same thing in my town. I don't want to piss away $40,000 + another $80,000 on maintenance and insurance and parking fees and bridge tolls on a self-driving car that will stand idle in my garage, or my employer's parking space for 23 hours of the day. I want better rail. I want more buses. I want to be able to ride a bike, without putting my life in the hands of lunatics who in any sane world, should not have been licensed to drive. Surely, we could deliver all that for the money we are currently wasting on automobiles?
      - cryptonector 7y ago
        I doubt you could deliver better rail for that money. Rail is fantastically expensive, and if you get the routes wrong, that's a forever mistake. Buses are another story, but even NYC, which has the density to support a fantastic bus system... has a crap bus system.
        vkou 7y ago
        Owning a car in a metro area is ~$8,000/year. There's 1.3 cars/household, so we're looking at ~$10,000/year/household. My metro area's per-household budget is ~$17,000/year. ~$4,000/year on that is spent on transportation, including public transit, roadway, and highway maintenance and construction. Tripling the transportation budget, at the expense of personal automobiles would absolutely deliver many of those things. NYC has a crap bus system, because they have to share roadways with automobiles, which are the cause of NYC gridlock. If buses had the right of way, they would work much better. And it doesn't take being Nostradamus to figure out at least a couple of good, new train routes - in any metro area. I'm sure you could find me some examples of train routes that were built, and then turned out to be under-utilized... But I feel that they would be the exceptions that prove the rule. Every major metro area is seeing population growth, so it's not like people will suddenly move away from the train lines. Not to mention that every line of rail tracks has the throughput of a super-highway[1], at much smaller footprint and cost (If you take into account the full cost of vehicle ownership.) [1] In Vancouver, any one of the three SkyTrain lines has a throughput of ~14 lanes of highway, during peak hour...
erentz 7y ago
> This ignores the potential drastic reduction of space allocated for parking, including space that is already part of roadways. Except that if a car isn’t in a car park then it’s on a street moving (circling, going to pick up a passenger, etc) and contributing to congestion (maybe more so for that reason as some other articles have speculated). So basic geometry of road capacity still applies.
- michaelt 7y ago
  If a car that would otherwise be parked for 8 hours in the city can instead drive 30 minutes back to the suburbs, park for 7 hours, then drive back in, we can trade 1 car-hour of freeway and 7 car-hours of suburban parking to regain 8 car-hours of city parking. And maybe we think that suburban parking is 'free' because it would have otherwise been sitting empty. Obviously within the constraints of that model it's still debatable whether that's a good deal, between the emissions and the doubling of near-rush-hour freeway traffic. And beyond that simple model, how cars performing pick-ups will impact congestion and whether people are willing to summon their cars 30 minutes in advance is also debatable.
  - CydeWeys 7y ago
    If every car did two daily round trip commutes into the city center instead of one, that would double congestion. I just don't see this being workable at all.
    - SketchySeaBeast 7y ago
      I don't like the idea, but I've noticed that in my city, if you're heading into the city centre you're absolutely out of luck as far as traffic is concerned, but if you're heading the other way, it's extremely light. So you wouldn't so much be "doubling" congestion as just applying it to both in and out flow equally. I don't know if that would actually cause more difficulties or not.
      - ant6n 7y ago
lucas_membrane 7y ago
This may be one of the rare usages of 'exponential' in the popular press that I can allow. The exponential aspect of urban growth may be apt -- the premise that the number of people who can find a reason to relocate to a city will vary in direct proportion to the number of people who are already there might hold with acceptable accuracy over some range, and departures may be negligible during some periods of rapid growth.
- brlewis 7y ago
  First use of "exponential growth" in the article was OK. I don't think the second use was. See https://news.ycombinator.com/item?id=20866372 https://news.ycombinator.com/item?id=20866372

human20190310 7y ago

I think "growing exponentially" is technically correct. Anything that grows at a rate proportional to its size is growing exponentially. The transportation innovations allowed cities to keep doing that, i.e. growing at X% per year instead of hitting some limit where population growth would force out-migration.

brlewis 7y ago
OK yes there's a reasonable use of the term early in the article that I overlooked. It was the "streetcars and bicycles" section where it grated on me.

blauditore 7y ago

> This ignores the potential drastic reduction of space allocated for parking How so? If you mean because of more car sharing, I don't think that's going to happen. Most people would still want their own car. If you mean because of being able to let the car park itself outside the city, or even drive home: That would drive up cost for the owner and reduce convenience (having to "order" it 30 minutes ahead of time). In addition, it would worsen congestion on streets due to cars moving more.

cryptonector 7y ago
I can imagine NYC with 1/10th the private cars and 4x the shared/rental/taxi cars, and traffic flowing much better than today owing to the additional bandwidth freed up by the 70-80% reduction in street-side parking space need. NYC residents just might accept the trade-off.
- kiliantics 7y ago
  As an NYC resident, I would much prefer to just have 1/10th the private cars, twice the number of trains (or whatever is necessary), and a massive reduction in the number of cars sitting around unused, with the resulting extra space being converted to green space, pedestrian-only areas, and bike lanes. Self-driving cars and the infrastructure they necessitate would make NYC more hostile to people, not less.
  - vkou 7y ago
    As a non-NYC resident, I would love to see the same thing in my town. I don't want to piss away $40,000 + another $80,000 on maintenance and insurance and parking fees and bridge tolls on a self-driving car that will stand idle in my garage, or my employer's parking space for 23 hours of the day. I want better rail. I want more buses. I want to be able to ride a bike, without putting my life in the hands of lunatics who in any sane world, should not have been licensed to drive. Surely, we could deliver all that for the money we are currently wasting on automobiles?
    - cryptonector 7y ago
      I doubt you could deliver better rail for that money. Rail is fantastically expensive, and if you get the routes wrong, that's a forever mistake. Buses are another story, but even NYC, which has the density to support a fantastic bus system... has a crap bus system.
      - vkou 7y ago
        Owning a car in a metro area is ~$8,000/year. There's 1.3 cars/household, so we're looking at ~$10,000/year/household. My metro area's per-household budget is ~$17,000/year. ~$4,000/year on that is spent on transportation, including public transit, roadway, and highway maintenance and construction. Tripling the transportation budget, at the expense of personal automobiles would absolutely deliver many of those things. NYC has a crap bus system, because they have to share roadways with automobiles, which are the cause of NYC gridlock. If buses had the right of way, they would work much better. And it doesn't take being Nostradamus to figure out at least a couple of good, new train routes - in any metro area. I'm sure you could find me some examples of train routes that were built, and then turned out to be under-utilized... But I feel that they would be the exceptions that prove the rule. Every major metro area is seeing population growth, so it's not like people will suddenly move away from the train lines. Not to mention that every line of rail tracks has the throughput of a super-highway[1], at much smaller footprint and cost (If you take into account the full cost of vehicle ownership.) [1] In Vancouver, any one of the three SkyTrain lines has a throughput of ~14 lanes of highway, during peak hour...

erentz 7y ago

> This ignores the potential drastic reduction of space allocated for parking, including space that is already part of roadways. Except that if a car isn’t in a car park then it’s on a street moving (circling, going to pick up a passenger, etc) and contributing to congestion (maybe more so for that reason as some other articles have speculated). So basic geometry of road capacity still applies.

michaelt 7y ago
If a car that would otherwise be parked for 8 hours in the city can instead drive 30 minutes back to the suburbs, park for 7 hours, then drive back in, we can trade 1 car-hour of freeway and 7 car-hours of suburban parking to regain 8 car-hours of city parking. And maybe we think that suburban parking is 'free' because it would have otherwise been sitting empty. Obviously within the constraints of that model it's still debatable whether that's a good deal, between the emissions and the doubling of near-rush-hour freeway traffic. And beyond that simple model, how cars performing pick-ups will impact congestion and whether people are willing to summon their cars 30 minutes in advance is also debatable.
- CydeWeys 7y ago
  If every car did two daily round trip commutes into the city center instead of one, that would double congestion. I just don't see this being workable at all.
  - SketchySeaBeast 7y ago
    I don't like the idea, but I've noticed that in my city, if you're heading into the city centre you're absolutely out of luck as far as traffic is concerned, but if you're heading the other way, it's extremely light. So you wouldn't so much be "doubling" congestion as just applying it to both in and out flow equally. I don't know if that would actually cause more difficulties or not.
    - ant6n 7y ago

lucas_membrane 7y ago

This may be one of the rare usages of 'exponential' in the popular press that I can allow. The exponential aspect of urban growth may be apt -- the premise that the number of people who can find a reason to relocate to a city will vary in direct proportion to the number of people who are already there might hold with acceptable accuracy over some range, and departures may be negligible during some periods of rapid growth.

brlewis 7y ago
First use of "exponential growth" in the article was OK. I don't think the second use was. See https://news.ycombinator.com/item?id=20866372 https://news.ycombinator.com/item?id=20866372