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> It's supposed to run on renewables be less energy intensive and incorporate "green" technologies Anyone can say that, but there is nothing apparently green a

> It's supposed to run on renewables be less energy intensive and incorporate "green" technologies Anyone can say that, but there is nothing apparently green about the design, whether you built it in the desert or on grass plains. Giant mirrors in the middle of the desert, is good for what? At least there isn't anything to scorch, I guess. The city is optimized to make travel distances as long as possible. No matter how you power those trains, shorter routes are more economical than longer routes.

kaikai 4y ago
Something that hadn’t occurred to me until I read your comment was that a single straight train line is very easy to control. Maybe the line is partially a bet on future instability and the need for authoritarian control over the population. Cities built organically have many roads and paths from point a to b.
- mc32 4y ago
  It's also easier to attack by an enemy. So it looks like they are betting on more peace. Alternatively, they could also have a large underground inhabitable volume.
  - closedloop129 4y ago
    To me, the project looks like a wall, sealing off Saudi Arabia from the rest of the world. With enough desalination, they can turn the peninsula into a green garden, kind of like India, powered by solar energy. I would say they are not betting on peace but on their need to shield their country from invaders.
mc32 4y ago
Well, it remains to be seen if this city is less "green" that existing designs --it only has to be better than current systems. "The city is optimized to make travel distances as long as possible." Only if you don't see it as many agglomerated cities built on a line. At least the intention is to have many self-contained "city" sections within the larger envelope. Yes, you may want to occasionally go to the other end, but not most people every day. With jobs being remote, there is less need to travel wen your job changes.
dominotw 4y ago
> The city is optimized to make travel distances as long as possible. Residents will be able to run errands with a five-minute walk;
chickenpotpie 4y ago
> The city is optimized to make travel distances as long as possible. No matter how you power those trains, shorter routes are more economical than longer routes. Not true. What's more economical: a train straight up a very steep mountain or a train winding around the mountain? There are many situations where it's more economical to build an intentionally longer route to save money. Imagine a billion person where every single person can take a train directly to every other person. If you arranged every person evenly spaced in a grid you could connect them with less travel than if they were in a very very long line. But the train system would be much much simpler.
- sethjr5rtfgh 4y ago
  > Not true. What's more economical: a train straight up a very steep mountain or a train winding around the mountain? Most of the energy is lost by slowing down to pick up people, not by taking turns.
s1artibartfast 4y ago
two points: First, I think the green goal is supporting the population with a single mega city instead of dozens of dirty cities. Regarding the travel, There is a lot of efficiency in having a single bus to support a city instead of spiderweb of connections. You can have trains with stops 100km, 50km, and 10, ect. If you compare a line and a grid, you have a lot less track and routes to support.
- idiotsecant 4y ago
  There isn't anything inherently 'cleaner' about a large city surrounded by a couple of mirrors vs a few dozen smaller ones. It certainly is guaranteed to be more expensive, though!
  - mc32 4y ago
    I don't get the mirrors either. If at least once faced south the walls could be covered in solar panels but mirrors? Who's going to clean the mirrors?
  - s1artibartfast 4y ago
    You cant really surround a 2 dimensional/grid city with mirrors because the perimeter is further from the interior. I think you can make a lot of arguments why a single city could in fact be cheaper than many smaller ones. Most boil down to efficiency of scale. 1 large transit system vs many. One large desalination plant vs many, one power grid instead of many, ect
adrianmonk 4y ago
> The city is optimized to make travel distances as long as possible. On the other hand, it's also optimized to reduce the number of dimensions of travel from 2 to 1. You never have to transfer from an east-west train to a north-south train (or vice versa). Literally everything is on your route. Transfers add time to your trip because instead of waiting for a train, boarding, and deboarding once, you do all of that twice. Your trip time isn't just time riding on the train. It's all that other stuff, too. (You probably still do have some transfers with local and express trains. That's an issue in 2D rail systems, too, but it's probably worse in 1D because of increased travel distances.) Combined trips also become easier. If two destinations lie in the same direction from your starting point, then one of them is directly on the way to the other. I'm not saying it's necessarily a net win, but it's at least a trade-off.
- blargey 4y ago
  > You never have to transfer from an east-west train to a north-south train (or vice versa). Literally everything is on your route. You can accomplish that in 2D by making the train line a ring, like the Yamanote Line of Tokyo. That way you halve the max distance traveled, and can “cut across” on car, foot, bike, other-train, etc where the main train line would still be inefficient.
  - adrianmonk 4y ago
    Yeah, that's an interesting idea. In fact my first thought was, why not make this a circle instead of a line? But they say it's going to have super high speed rail. From Wikipedia (https://en.wikipedia.org/wiki/The_Line%2C_Saudi_Arabia https://en.wikipedia.org/wiki/The_Line%2C_Saudi_Arabia): > The transportation layer will include a high-speed rail system, which is claimed to allow people to go from one side of the city to the other side in 20 minutes when finished, reaching a speed of 512 km/h, which is faster than existing high-speed rail at the time of announcement. Maybe they think a perfectly straight line makes that easier to build. Or maybe they just think their rail is so fast that distance becomes a minor issue. Future expansion is also interesting to think about. If you make it a line, you can expand by adding, say, 10% onto the end. Once you've built a circle, it's hard to make it 10% bigger. But I guess you could double a circle by adding another circle and turning it into a figure 8. The figure 8 would have similar advantages to a circle since they are both closed loops.

kaikai 4y ago

Something that hadn’t occurred to me until I read your comment was that a single straight train line is very easy to control. Maybe the line is partially a bet on future instability and the need for authoritarian control over the population. Cities built organically have many roads and paths from point a to b.

mc32 4y ago
It's also easier to attack by an enemy. So it looks like they are betting on more peace. Alternatively, they could also have a large underground inhabitable volume.
- closedloop129 4y ago
  To me, the project looks like a wall, sealing off Saudi Arabia from the rest of the world. With enough desalination, they can turn the peninsula into a green garden, kind of like India, powered by solar energy. I would say they are not betting on peace but on their need to shield their country from invaders.

mc32 4y ago

Well, it remains to be seen if this city is less "green" that existing designs --it only has to be better than current systems. "The city is optimized to make travel distances as long as possible." Only if you don't see it as many agglomerated cities built on a line. At least the intention is to have many self-contained "city" sections within the larger envelope. Yes, you may want to occasionally go to the other end, but not most people every day. With jobs being remote, there is less need to travel wen your job changes.

dominotw 4y ago

> The city is optimized to make travel distances as long as possible. Residents will be able to run errands with a five-minute walk;

chickenpotpie 4y ago

> The city is optimized to make travel distances as long as possible. No matter how you power those trains, shorter routes are more economical than longer routes. Not true. What's more economical: a train straight up a very steep mountain or a train winding around the mountain? There are many situations where it's more economical to build an intentionally longer route to save money. Imagine a billion person where every single person can take a train directly to every other person. If you arranged every person evenly spaced in a grid you could connect them with less travel than if they were in a very very long line. But the train system would be much much simpler.

sethjr5rtfgh 4y ago
> Not true. What's more economical: a train straight up a very steep mountain or a train winding around the mountain? Most of the energy is lost by slowing down to pick up people, not by taking turns.

s1artibartfast 4y ago

two points: First, I think the green goal is supporting the population with a single mega city instead of dozens of dirty cities. Regarding the travel, There is a lot of efficiency in having a single bus to support a city instead of spiderweb of connections. You can have trains with stops 100km, 50km, and 10, ect. If you compare a line and a grid, you have a lot less track and routes to support.

idiotsecant 4y ago
There isn't anything inherently 'cleaner' about a large city surrounded by a couple of mirrors vs a few dozen smaller ones. It certainly is guaranteed to be more expensive, though!
- mc32 4y ago
  I don't get the mirrors either. If at least once faced south the walls could be covered in solar panels but mirrors? Who's going to clean the mirrors?
- s1artibartfast 4y ago
  You cant really surround a 2 dimensional/grid city with mirrors because the perimeter is further from the interior. I think you can make a lot of arguments why a single city could in fact be cheaper than many smaller ones. Most boil down to efficiency of scale. 1 large transit system vs many. One large desalination plant vs many, one power grid instead of many, ect

adrianmonk 4y ago

> The city is optimized to make travel distances as long as possible. On the other hand, it's also optimized to reduce the number of dimensions of travel from 2 to 1. You never have to transfer from an east-west train to a north-south train (or vice versa). Literally everything is on your route. Transfers add time to your trip because instead of waiting for a train, boarding, and deboarding once, you do all of that twice. Your trip time isn't just time riding on the train. It's all that other stuff, too. (You probably still do have some transfers with local and express trains. That's an issue in 2D rail systems, too, but it's probably worse in 1D because of increased travel distances.) Combined trips also become easier. If two destinations lie in the same direction from your starting point, then one of them is directly on the way to the other. I'm not saying it's necessarily a net win, but it's at least a trade-off.

blargey 4y ago
> You never have to transfer from an east-west train to a north-south train (or vice versa). Literally everything is on your route. You can accomplish that in 2D by making the train line a ring, like the Yamanote Line of Tokyo. That way you halve the max distance traveled, and can “cut across” on car, foot, bike, other-train, etc where the main train line would still be inefficient.
- adrianmonk 4y ago
  Yeah, that's an interesting idea. In fact my first thought was, why not make this a circle instead of a line? But they say it's going to have super high speed rail. From Wikipedia (https://en.wikipedia.org/wiki/The_Line%2C_Saudi_Arabia https://en.wikipedia.org/wiki/The_Line%2C_Saudi_Arabia): > The transportation layer will include a high-speed rail system, which is claimed to allow people to go from one side of the city to the other side in 20 minutes when finished, reaching a speed of 512 km/h, which is faster than existing high-speed rail at the time of announcement. Maybe they think a perfectly straight line makes that easier to build. Or maybe they just think their rail is so fast that distance becomes a minor issue. Future expansion is also interesting to think about. If you make it a line, you can expand by adding, say, 10% onto the end. Once you've built a circle, it's hard to make it 10% bigger. But I guess you could double a circle by adding another circle and turning it into a figure 8. The figure 8 would have similar advantages to a circle since they are both closed loops.