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Even with perfect software how could cars, self-driven or otherwise, ever compete with rail? A four-track rail system has a per-track throughput of 100000 peop

Even with perfect software how could cars, self-driven or otherwise, ever compete with rail? A four-track rail system has a per-track throughput of 100000 people per hour. Freeways can get 2000 cars per hour per lane, and an average of 1.6 people per car works out to only 3200 people per hour. That's the theoretical best. Actual roadways never approach this figure.

noir_lord 11y ago
> Freeways can get 2000 cars per hour per lane I'm missing something, in a single lane at 60mph you would be able to get ((60 * 1608)/5) (assuming car is 5m long) = 19296. If we assume that there is 5m of seperation between every car (possible when all cars are automatically driven and communicate with each other) that's still 10k cars an hour. 4 lane highway, 40k an hour, assuming occupancy at 1.6 that's 64000 an hour. Human driven no way, we are too unpredictable and react far too slowly to safely drive in that way but computers probably could.
- thrownaway2424 11y ago
  Well you just made a pretty unfair comparison since you added up to 64000 for all four lanes vs 100000 people /per track/ on a 4-track railway. But I think your assumptions are all pretty optimistic. You wouldn't be able to run cars that close together on a multilane roadway because cars would need to move between lanes to enter and exit which would cause pipeline shocks if there was that little room. Anyway the main difference between my claims and yours is that yours are speculation, while mine are based on history. We've seen five million people disembark at actual railroad stations. It's happened. We don't have to speculate.
theptip 11y ago
I'm interested to dig into this question a bit more -- do you have any linkable resources that give more detail on those numbers? Thanks.
nostrademons 11y ago
They aren't mutually exclusive. An always-available self-driving car service would drastically help the usability of subways or commuter rail in the crucial last 2-3 miles. If I could hail a car to drive me the 2 miles to the Caltrain stop and then hail another one to drive me the 3-4 miles from 22nd St. to the Sunset, a much greater percentage of the city becomes available to me without a highway trip.

noir_lord 11y ago

> Freeways can get 2000 cars per hour per lane I'm missing something, in a single lane at 60mph you would be able to get ((60 * 1608)/5) (assuming car is 5m long) = 19296. If we assume that there is 5m of seperation between every car (possible when all cars are automatically driven and communicate with each other) that's still 10k cars an hour. 4 lane highway, 40k an hour, assuming occupancy at 1.6 that's 64000 an hour. Human driven no way, we are too unpredictable and react far too slowly to safely drive in that way but computers probably could.

thrownaway2424 11y ago
Well you just made a pretty unfair comparison since you added up to 64000 for all four lanes vs 100000 people /per track/ on a 4-track railway. But I think your assumptions are all pretty optimistic. You wouldn't be able to run cars that close together on a multilane roadway because cars would need to move between lanes to enter and exit which would cause pipeline shocks if there was that little room. Anyway the main difference between my claims and yours is that yours are speculation, while mine are based on history. We've seen five million people disembark at actual railroad stations. It's happened. We don't have to speculate.

theptip 11y ago

I'm interested to dig into this question a bit more -- do you have any linkable resources that give more detail on those numbers? Thanks.

nostrademons 11y ago

They aren't mutually exclusive. An always-available self-driving car service would drastically help the usability of subways or commuter rail in the crucial last 2-3 miles. If I could hail a car to drive me the 2 miles to the Caltrain stop and then hail another one to drive me the 3-4 miles from 22nd St. to the Sunset, a much greater percentage of the city becomes available to me without a highway trip.