4 ms·

There's no need to have only one line to connect everything, even in a linear structure. It's still about the topology. At the simplest there would be one line

There's no need to have only one line to connect everything, even in a linear structure. It's still about the topology. At the simplest there would be one line connecting from end to end, which should be the fastest and the one with the fewest stops. But then you have smaller lines, travelling in their own tubes, connecting local areas. That way you can travel between any two points relatively fast and avoid congestion. You can build redundancy into this system. But also, it's not a catastrophe on a normally 20 minute trip if there is blocked section and you have to walk a few minutes, take a local connection to bypass the blockage and then go on. Happens to me all the time... The big benefit in a linear city is that the transport pods never need to turn around. You also don't need to manufacture curved rails or things like that. You can build structures like that in a "2D" city, but it's harder.

amluto 4y ago
In 2D, you can build a grid of straight line railways. Riders transfer zero or one times. Cost scales proportionally to area (and hence population) assuming constant density. Time between two random points scales as sqrt(size). Ridership on a given rail segment scales like sqrt(size), which may be tolerable. In 1D, you can build a linear railway. Cost scales proportionally to length (and hence population) if you assume that the the railway merely needs to get longer as population grows, but this gives a system where ridership on a given rail segment scales linearly with population, which is much worse. Time between two random points also scales linearly with population. The added costs associated with improving performance given the worse scaling seem likely to blow the whole thing up.
- rdsubhas 4y ago
  Remember, this is still a 2D project. The second dimension is up! Instead of XZ axes, it's XY. Your point about length is true, but about population scale might not, because it's still in 2D. There are still ways to segregate tracks.
  - bobthepanda 4y ago
    Vertical poses a lot more problems than horizontal, though. As a general example, fire generally makes it unsafe to operate anything above or below.
- spywaregorilla 4y ago
  > In 2D, you can build a grid of straight line railways. Riders transfer zero or one times. Cost scales proportionally to area (and hence population) assuming constant density. Time between two random points scales as sqrt(size). Ridership on a given rail segment scales like sqrt(size), which may be tolerable. I doubt this would work. Cities don't do this for a reason. Transit lines get built according to transportation needs, not mathematical coverage of the space. You have pockets of housing that need to get to pockets of commerce. You can't practically run transit cars connecting [0,0] and [end, 0].
  - bobthepanda 4y ago
    A lot of big city metro networks look like grids in the city center, or effectively function as such. Farther out the grid is plugged in by bus.
    - spywaregorilla 4y ago
      Can you provide an example of a city with a grid-like metro? I know many grid like cities. I cannot think of any grid like metros.
      - bobthepanda 4y ago
        Grid like comes with a caveat. Most grids are only in city center (so that lines can connect to every other line in the city with most demand), and subways are not often grids but rather interlocking L shapes and curves depending on which radial direction out of city center got to have a subway first (but usually you can still see distinct gridlike patterns). And then there's geographic impediments like where streets and parks are. Beijing is a grid: https://upload.wikimedia.org/wikipedia/commons/0/07/Beijing_Subway_System_Map.svg https://upload.wikimedia.org/wikipedia/commons/0/07/Beijing_... Shanghai is a grid: https://en.wikipedia.org/wiki/Shanghai_Metro#/media/File:Shanghai_Metro_Network_en.png https://en.wikipedia.org/wiki/Shanghai_Metro#/media/File:Sha... Tokyo is grid-like east and south of the Imperial Palace: https://i0.wp.com/transitmap.net/wp-content/uploads/2020/11/Tokyo-Metro-Map-Mejia_2500px.jpg https://i0.wp.com/transitmap.net/wp-content/uploads/2020/11/... Taipei has a grid: https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 The gridded portion of Manhattan has a grid between 14th St and Central Park: https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38. Buses fill out the grid in outer areas like the Bronx: https://new.mta.info/map/5366 https://new.mta.info/map/5366 Paris is gridded about as much as it can be due to the non-grid road layout: https://www.ratp.fr/sites/default/files/plans-lignes/Plans-essentiels/Plan-Metro.1653922257.pdf https://www.ratp.fr/sites/default/files/plans-lignes/Plans-e... Berlin is gridlike: https://sbahn.berlin/en/route-map/ https://sbahn.berlin/en/route-map/
- bayesian_horse 4y ago
  It's harder to build a grid of straight railways. You need more bridging or crossing at the very least. You are right about 2D being more efficient in terms of the length between two random points, but there could be scenarios where the simplicity still outweighs that benefit, especially given all the other factors in this project, like sunlight. The length is also much less of a concern than in traditional transport systems because of less friction and less need to brake, so most of the energy is for accelerating and decelerating at the stops. Of course it would blow up if you wanted to build a fully connected city that is twice that length or even longer, but that's not proposed.
  - bobthepanda 4y ago
    I’d assume this linear city would also involve a lot of bridging, since due to the width trains would basically almost be on top of each other. Trains crossing perpendicular have to bridge maybe 6m at most. You’d have to bridge the entire length of city for this. And a fire would render any lines above or below unsafe to run until extinguished.

amluto 4y ago

In 2D, you can build a grid of straight line railways. Riders transfer zero or one times. Cost scales proportionally to area (and hence population) assuming constant density. Time between two random points scales as sqrt(size). Ridership on a given rail segment scales like sqrt(size), which may be tolerable. In 1D, you can build a linear railway. Cost scales proportionally to length (and hence population) if you assume that the the railway merely needs to get longer as population grows, but this gives a system where ridership on a given rail segment scales linearly with population, which is much worse. Time between two random points also scales linearly with population. The added costs associated with improving performance given the worse scaling seem likely to blow the whole thing up.

rdsubhas 4y ago
Remember, this is still a 2D project. The second dimension is up! Instead of XZ axes, it's XY. Your point about length is true, but about population scale might not, because it's still in 2D. There are still ways to segregate tracks.
- bobthepanda 4y ago
  Vertical poses a lot more problems than horizontal, though. As a general example, fire generally makes it unsafe to operate anything above or below.
spywaregorilla 4y ago
> In 2D, you can build a grid of straight line railways. Riders transfer zero or one times. Cost scales proportionally to area (and hence population) assuming constant density. Time between two random points scales as sqrt(size). Ridership on a given rail segment scales like sqrt(size), which may be tolerable. I doubt this would work. Cities don't do this for a reason. Transit lines get built according to transportation needs, not mathematical coverage of the space. You have pockets of housing that need to get to pockets of commerce. You can't practically run transit cars connecting [0,0] and [end, 0].
- bobthepanda 4y ago
  A lot of big city metro networks look like grids in the city center, or effectively function as such. Farther out the grid is plugged in by bus.
  - spywaregorilla 4y ago
    Can you provide an example of a city with a grid-like metro? I know many grid like cities. I cannot think of any grid like metros.
    - bobthepanda 4y ago
      Grid like comes with a caveat. Most grids are only in city center (so that lines can connect to every other line in the city with most demand), and subways are not often grids but rather interlocking L shapes and curves depending on which radial direction out of city center got to have a subway first (but usually you can still see distinct gridlike patterns). And then there's geographic impediments like where streets and parks are. Beijing is a grid: https://upload.wikimedia.org/wikipedia/commons/0/07/Beijing_Subway_System_Map.svg https://upload.wikimedia.org/wikipedia/commons/0/07/Beijing_... Shanghai is a grid: https://en.wikipedia.org/wiki/Shanghai_Metro#/media/File:Shanghai_Metro_Network_en.png https://en.wikipedia.org/wiki/Shanghai_Metro#/media/File:Sha... Tokyo is grid-like east and south of the Imperial Palace: https://i0.wp.com/transitmap.net/wp-content/uploads/2020/11/Tokyo-Metro-Map-Mejia_2500px.jpg https://i0.wp.com/transitmap.net/wp-content/uploads/2020/11/... Taipei has a grid: https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 The gridded portion of Manhattan has a grid between 14th St and Central Park: https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38 https://english.metro.taipei/cp.aspx?n=1BE0AF76C79F9A38. Buses fill out the grid in outer areas like the Bronx: https://new.mta.info/map/5366 https://new.mta.info/map/5366 Paris is gridded about as much as it can be due to the non-grid road layout: https://www.ratp.fr/sites/default/files/plans-lignes/Plans-essentiels/Plan-Metro.1653922257.pdf https://www.ratp.fr/sites/default/files/plans-lignes/Plans-e... Berlin is gridlike: https://sbahn.berlin/en/route-map/ https://sbahn.berlin/en/route-map/
bayesian_horse 4y ago
It's harder to build a grid of straight railways. You need more bridging or crossing at the very least. You are right about 2D being more efficient in terms of the length between two random points, but there could be scenarios where the simplicity still outweighs that benefit, especially given all the other factors in this project, like sunlight. The length is also much less of a concern than in traditional transport systems because of less friction and less need to brake, so most of the energy is for accelerating and decelerating at the stops. Of course it would blow up if you wanted to build a fully connected city that is twice that length or even longer, but that's not proposed.
- bobthepanda 4y ago
  I’d assume this linear city would also involve a lot of bridging, since due to the width trains would basically almost be on top of each other. Trains crossing perpendicular have to bridge maybe 6m at most. You’d have to bridge the entire length of city for this. And a fire would render any lines above or below unsafe to run until extinguished.