4 ms·

From an energetics perspective it's incredibly hard to beat walking, biking or rails. If your occupancy on the car is reliably greater than 1, that is an improv

From an energetics perspective it's incredibly hard to beat walking, biking or rails. If your occupancy on the car is reliably greater than 1, that is an improvement over single occupancy cars, but those boxes are just huge compared to a bicycle.

abecedarius 3y ago
Once it makes economic sense to design car models specifically for robotaxi use, small light one-passenger electric models may well become the most common type. In the graph I linked from my other reply, a one-person E.V. like this beat all of the transit systems and came in second only to an electric scooter/trike.
- pfsalter 3y ago
  Still more cost efficient to run a single bus than separate vehicles, just in maintenance alone. Also we already have buses, these single occupation EVs that still have enough space for a decent battery size don't exist.
  - xnx 3y ago
    These seems reasonable, but I don't think the math holds up. A 2016 study (http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20Transit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20...) showed the lifetime cost (including maintenance) of a bus for its 12 year useful lifespan to be $1.4 million. Without even doing the inflation adjustment, that could buy at least 12 electric vehicles. Those 12 vehicles could be much more efficient even running on a single fixed bus route (i.e. more frequent schedule), or (more likely) operating like taxis by taking people to and from exactly where they want to go.
HALtheWise 3y ago
I spouted this line for a long time, but was recently corrected by commenters pointing out that 2-3 occupancy electric cars actually beat the vast majority of subways and trains in practice, because you don't need to accelerate and decelerate every passenger at every possible stop. Cars are designed to be remarkably aerodynamically efficient, especially compared to motorcycles or bicycles, and an electric battery+motor is much more efficient at producing power than your muscles. Delivering on this requires some sort of "Uber Pool" like algorithm to put a few people together in a vehicle, but doesn't require large busses.
- RivieraKid 3y ago
  Maybe in some type of energy efficiency, but the push for public transit is not really about energy - it's about making cities pleasant places.
- bobthepanda 3y ago
  In cities where space is at a premium, a bunch of people standing, or on a bicycle, will always beat out people sitting down with room for an engine and a trunk. Average occupancy of a car is 1.5 in the US, and that number shrinks as household size declines. (It’s also worth noting that there’s no reason that automated technologies wouldn’t also spread to buses and trains. In fact, you can already automate trains. The big win there, is that buses represent massive fleet commonality.)
  - xnx 3y ago
    Keep going with that thinking. What if trains were autonomous, electric, exactly/efficiently sized to what they were transporting, didn't require expensive/dedicated tracks, and could go directly between any 2 points? You end up with autonomous vehicles.
    - bobthepanda 3y ago
      Trains are nice because they don’t require massive reconfigurations to hold varying crowds of people and the things they carry. People move furniture on subways all the time. There isn’t really a ‘perfectly sized’ personal vehicle; even now, just the simple bifurcation between a normal and XL taxi leads to longer waits for the latter, and god forbid you need special accommodations like for a wheelchair. Car-like vehicles have massive inefficiencies, because the act of merging into and out of other lanes is inefficient. A train line can carry up to 80k people per direction per hour. The FHWA’s estimate of a car lane car capacity is 2k people per direction per hour. And because cars have to eventually dump onto a surface network that requires timed cycles so that pedestrians and cyclists can cross the street, these low capacity segments are actually the bottleneck.
  - Chathamization 3y ago

abecedarius 3y ago

Once it makes economic sense to design car models specifically for robotaxi use, small light one-passenger electric models may well become the most common type. In the graph I linked from my other reply, a one-person E.V. like this beat all of the transit systems and came in second only to an electric scooter/trike.

pfsalter 3y ago
Still more cost efficient to run a single bus than separate vehicles, just in maintenance alone. Also we already have buses, these single occupation EVs that still have enough space for a decent battery size don't exist.
- xnx 3y ago
  These seems reasonable, but I don't think the math holds up. A 2016 study (http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20Transit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20...) showed the lifetime cost (including maintenance) of a bus for its 12 year useful lifespan to be $1.4 million. Without even doing the inflation adjustment, that could buy at least 12 electric vehicles. Those 12 vehicles could be much more efficient even running on a single fixed bus route (i.e. more frequent schedule), or (more likely) operating like taxis by taking people to and from exactly where they want to go.

HALtheWise 3y ago

I spouted this line for a long time, but was recently corrected by commenters pointing out that 2-3 occupancy electric cars actually beat the vast majority of subways and trains in practice, because you don't need to accelerate and decelerate every passenger at every possible stop. Cars are designed to be remarkably aerodynamically efficient, especially compared to motorcycles or bicycles, and an electric battery+motor is much more efficient at producing power than your muscles. Delivering on this requires some sort of "Uber Pool" like algorithm to put a few people together in a vehicle, but doesn't require large busses.

RivieraKid 3y ago
Maybe in some type of energy efficiency, but the push for public transit is not really about energy - it's about making cities pleasant places.
bobthepanda 3y ago
In cities where space is at a premium, a bunch of people standing, or on a bicycle, will always beat out people sitting down with room for an engine and a trunk. Average occupancy of a car is 1.5 in the US, and that number shrinks as household size declines. (It’s also worth noting that there’s no reason that automated technologies wouldn’t also spread to buses and trains. In fact, you can already automate trains. The big win there, is that buses represent massive fleet commonality.)
- xnx 3y ago
  Keep going with that thinking. What if trains were autonomous, electric, exactly/efficiently sized to what they were transporting, didn't require expensive/dedicated tracks, and could go directly between any 2 points? You end up with autonomous vehicles.
  - bobthepanda 3y ago
    Trains are nice because they don’t require massive reconfigurations to hold varying crowds of people and the things they carry. People move furniture on subways all the time. There isn’t really a ‘perfectly sized’ personal vehicle; even now, just the simple bifurcation between a normal and XL taxi leads to longer waits for the latter, and god forbid you need special accommodations like for a wheelchair. Car-like vehicles have massive inefficiencies, because the act of merging into and out of other lanes is inefficient. A train line can carry up to 80k people per direction per hour. The FHWA’s estimate of a car lane car capacity is 2k people per direction per hour. And because cars have to eventually dump onto a surface network that requires timed cycles so that pedestrians and cyclists can cross the street, these low capacity segments are actually the bottleneck.
- Chathamization 3y ago