← Back to context

Comment by jv22222

9 years ago

Is it really wasteful? It seems like it is an ever moving system. In terms of people capacity it seems it would carry more by being always flowing vs a stopping starting transit system.

9 comments

jv22222

Reply
osdiab  9 years ago

The amount of people that can fit in 1 car is roughly maxes out at 4-7 people, depending on the car. There needs to be enough spacing between each car so that in the case of a failure, cars have space to brake to a stop without catapulting the people in it, or causing them to become overly nauseous. So there's going to be a decent amounnt of spacing between each car.

The number of people that can fit on 1 bus can hit in the ballpark of 50 people, so we're getting a roughly 10x capacity boost here. You lose the "ever-moving system" benefit doing this, but I highly doubt some stopping and starting would lead to an order of magnitude slower speed.

Now, the number of people that can fit on 1 SF BART train is in the realm of 10 cars * 200 = 2000 people per train. The spacing is not going to be on the order of 100x longer than in the individual car case, and the starting-stopping speed is going to be not a bit slower than the bus case.

I'll let you work out the math on that, but it's not even orders of magnitude close. Don't need to be a "visionary" to see that.

  • Retric  9 years ago

    A well managed train system can manage 1 car per line per 5 minutes. 2000 * 60 / 5 = 24,000 people per hour. Highways can handle 2,000 - 2200 vehicles per lane or so at the low end 1/12 but that's very much an edge case. Most lines are closer to one train every 20 minutes and you can average 3 people per car which makes them equivalent.

    The real issue is not highways, but what happens when people try and get off or onto them. It's possible but rare to do this well.