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What is the route capacity for a lane of freeway vs a rail line? I assumed it’s the opposite, since a freeway has continuous throughout while a rail line is dis

What is the route capacity for a lane of freeway vs a rail line? I assumed it’s the opposite, since a freeway has continuous throughout while a rail line is discrete, but I don’t have a good intuition for comparing the scale of each mode.

dragonwriter 4y ago
> What is the route capacity for a lane of freeway vs a rail line? I assumed it’s the opposite, since a freeway has continuous throughout while a rail line is discrete According to this book (which provides assumptions and calculations supporting) [0], 10:1 in favor of rail, as a conservative estimate. https://eng.libretexts.org/Bookshelves/Industrial_and_Systems_Engineering/Book%3A_The_Art_of_Insight_in_Science_and_Engineering_(Mahajan)/01%3A_Part_I-_Organizing_Complexity/01%3A_Divide_and_Conquer/1.02%3A_Rails_vs_Roads#:~:text=How%20does%20the%20capacity%20of,capacity%20of%20a%20train%20line%3F&text=This%20capacity%20is%20ten%20times,single%20fast%2Dflowing%20highway%20lane https://eng.libretexts.org/Bookshelves/Industrial_and_System....
- cyberax 4y ago
  > A rush-hour train may consist of 20 cars The author is smoking some hard crack.
  - AnimalMuppet 4y ago
    Well, BART has no problem running 9-car trains. I don't know if that's rush hour or not, but I've seen them. If the rest of the math is right, that still gets you 4.5-to-1 in favor of rail.
    - dragonwriter 4y ago
      BART (mainline) runs a maximum of 10 car trains, with a “crush” (maximum) capacity of 200+ per car.
    - cyberax 4y ago
      Have you ever walked past a 20-car train? It's way too long for commuting. There will be no way to build platforms for it unless you're doing a full green-field build.
    - snovv_crash 4y ago
      Europe has plenty of double-story trains. I agree 10 is about the limit otherwise the station sizes aren't people friendly.
      - Symbiote 4y ago
        The Eurostar trains between London and Brussels/Paris/Amsterdam have 16-18 coaches, although they are noticeably long. (Other than night trains, I'd expect these to be the longest in Europe.)
bluGill 4y ago
How do you calculate capacity? Safety engineers keep yelling that drivers need to keep 3 seconds between cars, but in reality they most drive about .3 seconds from the car in front. There is nearly a 10x difference in freeway capacity between just those two. Trains tend to maintain longer distances, but if you want to ignore safety we can follow a lot closer.
adgjlsfhk1 4y ago
The big difference is that in a train, you fit 4 people wide and roughly 2-3 ft front to back per person while in cars which have average capacity of ~1.5 per car, you have 1.5 people wide and 50-200 ft front to back. Trains are farther apart than cars, but fit a ton of people per train.

dragonwriter 4y ago

> What is the route capacity for a lane of freeway vs a rail line? I assumed it’s the opposite, since a freeway has continuous throughout while a rail line is discrete According to this book (which provides assumptions and calculations supporting) [0], 10:1 in favor of rail, as a conservative estimate. https://eng.libretexts.org/Bookshelves/Industrial_and_Systems_Engineering/Book%3A_The_Art_of_Insight_in_Science_and_Engineering_(Mahajan)/01%3A_Part_I-_Organizing_Complexity/01%3A_Divide_and_Conquer/1.02%3A_Rails_vs_Roads#:~:text=How%20does%20the%20capacity%20of,capacity%20of%20a%20train%20line%3F&text=This%20capacity%20is%20ten%20times,single%20fast%2Dflowing%20highway%20lane https://eng.libretexts.org/Bookshelves/Industrial_and_System....

cyberax 4y ago
> A rush-hour train may consist of 20 cars The author is smoking some hard crack.
- AnimalMuppet 4y ago
  Well, BART has no problem running 9-car trains. I don't know if that's rush hour or not, but I've seen them. If the rest of the math is right, that still gets you 4.5-to-1 in favor of rail.
  - dragonwriter 4y ago
    BART (mainline) runs a maximum of 10 car trains, with a “crush” (maximum) capacity of 200+ per car.
  - cyberax 4y ago
    Have you ever walked past a 20-car train? It's way too long for commuting. There will be no way to build platforms for it unless you're doing a full green-field build.
  - snovv_crash 4y ago
    Europe has plenty of double-story trains. I agree 10 is about the limit otherwise the station sizes aren't people friendly.
    - Symbiote 4y ago
      The Eurostar trains between London and Brussels/Paris/Amsterdam have 16-18 coaches, although they are noticeably long. (Other than night trains, I'd expect these to be the longest in Europe.)

bluGill 4y ago

How do you calculate capacity? Safety engineers keep yelling that drivers need to keep 3 seconds between cars, but in reality they most drive about .3 seconds from the car in front. There is nearly a 10x difference in freeway capacity between just those two. Trains tend to maintain longer distances, but if you want to ignore safety we can follow a lot closer.

adgjlsfhk1 4y ago

The big difference is that in a train, you fit 4 people wide and roughly 2-3 ft front to back per person while in cars which have average capacity of ~1.5 per car, you have 1.5 people wide and 50-200 ft front to back. Trains are farther apart than cars, but fit a ton of people per train.