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A full train on the Singapore North East Line can carry 1920 passengers (at 6 passengers/m^2), and at rush hour it runs 1 train per 2 or 3 minutes, so it carrie

A full train on the Singapore North East Line can carry 1920 passengers (at 6 passengers/m^2), and at rush hour it runs 1 train per 2 or 3 minutes, so it carries 16 passengers/second. A fully loaded Toyota Corolla carries five people and is 4.65 meters long, so at 100 km/h each lane of the highway would carry 30 passengers/second. So the highway would carry several times more passengers than the subway. Even though each train can pack more passengers per square meter than a car, it's not possible to run the trains back-to-back at 100 km/h, because they need to stop to let passengers off and on. At rush hour, the rate of the subway system is basically limited by how quickly people can flow from the platform into the train.

xvedejas 8y ago
A fully-utilized freeway in the way you describe is one that cars cannot easily get on/off of (where is the space for them?). They will have to wait at the on-ramp to be scheduled into a slot. Because of this, the average throughput of a highway necessarily is less than the max-speed max-packed scenario, since the bottleneck is actually the on/off-ramps and feeder streets.
- vilhelm_s 8y ago
  Of course, but the comment I replied to says that the max-speed max-packed scenario has much less throughput than a subway. That's completely wrong, and it's important to point out that it's wrong in order to see where the actual bottlenecks are (at the on/off ramps and feeder streets).
Johnny555 8y ago
You're ignoring space between cars, even with full automation you can't have a highway full of cars with no space between them, else there'd be no room for cars to merge on/off the freeway, and any traffic disruption would cause an immediate traffic back-up. Add one car length of distance and that puts the train in the same ballpark as the freeway lane. (I'll ignore the challenge of filling the Corolla with 5 people - I don't want to be the guy stuck in the middle seat) Though the problem isn't just throughput of the freeway, but also a question of where all of those cars are going to go when they get to the destination -- generally the commute traffic is going the same place at the same time. Self driving cars may not need a parking space, but if they are going to drop off passengers and then drive away to park somewhere outside of the city center, that causes even more city traffic. because they need to stop to let passengers off and on. At rush hour, the rate of the subway system is basically limited by how quickly people can flow from the platform into the train. That's why large train stations have multiple tracks.

xvedejas 8y ago

A fully-utilized freeway in the way you describe is one that cars cannot easily get on/off of (where is the space for them?). They will have to wait at the on-ramp to be scheduled into a slot. Because of this, the average throughput of a highway necessarily is less than the max-speed max-packed scenario, since the bottleneck is actually the on/off-ramps and feeder streets.

vilhelm_s 8y ago
Of course, but the comment I replied to says that the max-speed max-packed scenario has much less throughput than a subway. That's completely wrong, and it's important to point out that it's wrong in order to see where the actual bottlenecks are (at the on/off ramps and feeder streets).

Johnny555 8y ago

You're ignoring space between cars, even with full automation you can't have a highway full of cars with no space between them, else there'd be no room for cars to merge on/off the freeway, and any traffic disruption would cause an immediate traffic back-up. Add one car length of distance and that puts the train in the same ballpark as the freeway lane. (I'll ignore the challenge of filling the Corolla with 5 people - I don't want to be the guy stuck in the middle seat) Though the problem isn't just throughput of the freeway, but also a question of where all of those cars are going to go when they get to the destination -- generally the commute traffic is going the same place at the same time. Self driving cars may not need a parking space, but if they are going to drop off passengers and then drive away to park somewhere outside of the city center, that causes even more city traffic. because they need to stop to let passengers off and on. At rush hour, the rate of the subway system is basically limited by how quickly people can flow from the platform into the train. That's why large train stations have multiple tracks.