Comment by bobthepanda | Hacker News Reader

Comment by bobthepanda | Hacker News Reader

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Of course there will be changes. But the subways and light rails will still be required for a certain level of throughput. The New York City subway, for example, carries 60K people per hour per direction on a pair of tracks, while a car lane carries somewhere in the range of 2K per hour per direction. Self driving cars may improve lane utilization, but not by up to 30x. Shoving people into cattle cars hurtling down a track is just more space-efficient than dedicating an engine and seats for at most four people at a time.

Scooters and bikes have an effective range, particularly in places like LA that can have quite long commute distances.

Motive power source doesn't really change much.

Intra-urban flight would increase required energy for transport a lot and also move the crapshoot that is today's roads and traffic above our heads, ready to hurtle down at us.

Boring tunnels being cheaper has yet to be proven, since the main issues with tunneling are that tunnels have to be tailored to ground conditions.

Shuttles to Mars doesn't change how I get to and from work across town, the same way that airplanes did not.

Shouldn't a bus have similar throughput to a subway though, with no traffic?

Embarking and disembarking passengers takes much longer on a bus.

On the Select Bus Service (certain express routes) in NYC, passengers buy tickets outside the bus and ticket inspectors spot check them during the ride, similar to trains. Passengers can get on through the back door as well. This significantly improves embarkation time, making it similar to a train.

Subways have multiple cars per train, anywhere from 1 to 10, most places falling into 4-6. A bus has one; even articulated buses usual have a smaller capacity than a single subway car.

No - subway trains can travel 50 mph or more - a bus can’t do that on city centre roads.

In theory, but NYCs rarely go that fast. This is changing though. I saw a news article recently about how they are lifting the speed limits on some sections of track as repaired signals come online.

Though this probably counts as rarely, least some of the trunk line I've been on give the illusion of high-ish speeds. Examples: - Queens Blvd express (Forest Hills to Roosevelt Ave, Roosevelt to 36 St) - 7 Ave IRT express (from far downtown to 96th St) - Lexington express (City Hall to 125th, save for going through the switches south of 42nd St)

The DC Metro averages 33 mph, including stops. I’d be surprised if NYC’s express lines didn’t hit 50 routinely.

They do not, the max speed limits on rare long stretches of track are around 45 mph. Most stretches are well below this.

https://ny.curbed.com/2018/12/19/18146933/mta-new-york-subwa...

It is worth noting that NYC and DC have fundamentally different design philosophies that result in different average speeds.

New York's system is designed around walking to stations. All the way to the end of the lines, stations tend to be about a half mile apart. There are express lines but even those become locals on at least one end, with half-mile stop spacing.

DC's is an auto-oriented system, where you're expected to drive to the stop and then take the train in from the suburbs. As a result, while there is dense stop spacing in the center, distances between stations in the suburbs get progressively longer and longer. It's over these long stretches in the suburbs that DC is able to attain much higher speeds.

>No - subway trains can travel 50 mph or more - a bus can’t do that on city centre roads.

If you have really comprehensive coverage in a densely built area you'd be stopping too often for those top speeds to matter.

This is the problem with the Acela. It can technically go up to 150mph, but it has to stop so often that it averages 60mph for the journey.

For longer distances with limited stops, the speed and shigh capacity of a train are good. But to really fill out coverage in a dense area, short wait times and short distances between stops and destinations should be your chief considerations. Buses and streetcars just do that better. Though really, once you get past a certain level of density you need all of the above.

A single bus can move about 100-200 people. A single subway train can move about 1000-1500 people, an order of magnitude more.

wouldn't it be more fair to compare a single subway car with a bus? nothing stops you from running a "train" of buses.

It isn't really that fair, the critical time sink starts shifting to offload/onload time and there is a lot of waste having to load each bus individually.

This is why developed subway systems with high usage end up with large trains, that's the best way to speed up the system, reducing the delay caused by trains waiting for other trains that are stopped in the station.

Even a "train" of two buses is impractical for most bus routes because of the weight, poor turning radius and so on. I'm pretty sure going any longer than two is virtually impossible.

A single bus has 25-40 seats, so those other 160 people are going to be pretty miserable.

An articulated bus might be able to move closer to 100 people comfortably.

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