4 ms·

That "train passing occasionally" holds the equivalent of hundreds of cars. A random crappy light rail line will do the equivalent of 5 lanes of traffic (each

• mike_hearn 2y ago
  These comparisons are never quite apples-to-apples because the heavy rail line assumes only a few passengers have any luggage and that the entire line is used only for passengers, whereas the capacity rating for a road allows everyone to take large amounts of luggage and freight is always mixed in as well. You also have to take into account all the other factors that make roads preferable, for example, that rail capacity number assumes perfect utilization. In practice railways often have lots of downtime due to overnight shutdowns, broken signals/trains and labor strikes. None of these affect the roads.
  • slyall 2y ago
    You are moving the goalposts here. However if you want to compare mixed freight and passenger lines then rail equals many, many lanes. Plenty of rail cars have room for luggage too or even baggage cars. Usually we are talking about people going to/from work however hence most people are not carrying lots. Are you really saying your roads don't have shutdowns for maintenance? Or other problems? Also it is pretty rare for either roads nor railways to be fully utilised overnight. Also note that plenty of rail systems do run overnight.
    • telotortium 2y ago
      Rail can support freight of course and complements trucks very well. Rapid transit can’t really support freight if it wants to operate at any reasonable frequency - you just can’t load any real quantity of freight in a few minutes. Even baggage is stretching it a lot of the time on busy lines. And the slow acceleration times and length of freight trains severely conflicts with the needs of passenger rail. Therefore, freight and passenger rail need to be separated for either to perform well. On the other hand, cars and trucks are a lot more similar in performance and size, so they can share the same roads just fine - it’s only an issue if the road is completely choked with trucks.
  • tialaramex 2y ago
    Where can I buy these roads that don't require maintenance ? Cars that never break down ? Road traffic signals that never fail ? For the first I'm asking for a friend as the road outside her front door is currently torn open for a whole month and it sure seems like "Just magically never do that" would have been a better option if you insist it's so easy. The lines near me have freight on them (I live in a port city, a noticeable fraction of the country's imports and exports go via intermodal containers on trains) and still run like two services to London and two to other big cities per hour. The freight has to fit in between passenger services, that's a policy decision and the US just picked wrong.
    • mike_hearn 2y ago
      Roads can tolerate a lot of damage and be repaired whilst still in use (at less capacity). Capacity might fall but repairs are signalled in advance and people can plan around them, traffic will flow anyway. In places with big rail networks you're going to hear "I didn't make it into work this morning because of signal failures" really often. And when railways are repaired they will be totally closed for months. They're just way more brittle and unable to degrade gracefully.
    • Gibbon1 2y ago
      One thing I try to do is read stuff from people whose job it is to do stuff. What I read from transportation people is that for dense urban areas cars are inefficient at loading and unloading. And self driving cars are the worst. My rando observation is the few times something has gone really wrong on BART traffic is bad enough that it'd be better to take the day off. Ditto if a truck overturns on one of the bridges. And the latter happens way more often than the former. Reminds me after the Loma Prieta earthquake the bay bridge was out for a month but BART was running 12 hours later.
      • telotortium 2y ago
        By “transportation people” do you mean rail fans or avid cyclists? It’s an easy mistake to make - civil engineers with a more favorable attitude to cars (or even to rail) are more likely to be employed and therefore relatively quiet than rail fans or cyclists, who spend their time doing advocacy.
• jillesvangurp 2y ago
  The New York subway moves 3.2 million people per day. Taxis and ride share options are together good for about 1 million. Mostly non autonomous and polluting of course. If you triple that with autonomous vehicles that use the road smarter, it sounds doable to match what the subway is moving around. And of course people would be using these for point to point traffic and cars would be able to re-route based on traffic as well. We'll see how this plays out.
  • vincnetas 2y ago
    and now compare how much land surface metro needs and how much cars. and are you sure that current streets would fit 3x cars.