4 ms·

Given enough density, transit will never be "obsoleted by automated cars". It might be true in the suburbs where transit is highly inefficient and road space ab

by erispoe 10y ago

Given enough density, transit will never be "obsoleted by automated cars". It might be true in the suburbs where transit is highly inefficient and road space abundant relative to the population. But automated or not, cars are still an order of magnitude or two less space efficient than mass transit for moving people around. A rail line can move as much as 20 car lanes today. Even if you double the space efficiency of cars with automation (a long shot considering you still need to accommodate for pedestrians, cycles...), transit will keep being vastly more efficient. Automated cars will optimize parking and make on demand transit more affordable in the suburbs, but it will not solve transportation in dense cities. LA is a dense place on average. The greater LA is more dense than the greater NY.

Zigurd 10y ago
Automated vehicles will come in a range of sizes, from 2-seat pods to, at least, mini-bus sizes. Currently we have about the worst utilization of vehicles possible. Drivers drive alone, and park their cars for long intervals. This is why one can claim that trains move enough people to fill 20 car lanes. At the other end of the spectrum, diesel busses are noisy, smokey, need a professional driver, and go from underutilized to packed, depending on time of day. A mix of automated vehicles will be able to much more closely approach optimal load factors at all times of day. 6 or 8 passengers can ride in a car-sized automated vehicle. That makes streets a lo-capex alternative to rail.
- erispoe 10y ago
  With bigger vehicles, it becomes very impractical to not run them on a fixed route. Pairing people together works well enough, given enough demand, on UberPool and Lyft Line, it's inefficient for the bus sized vehicles you need to use street space efficiently. You need to pair routes while maintaining an acceptable waiting time. Automated or not, mass transit is just geometrically way more efficient, there's no way around it in dense urban environments. Your argument might be valid for a mid-sized american city, or a suburb, but it doesn't work for a european city, or even a dense american downtown.
  - Zigurd 10y ago
    > Automated or not, mass transit is just geometrically way more efficient Actually diesel busses are only "efficient" when they are full. They're barely as efficient as single occupant cars just on fuel use when you factor in the bus running underutilized much of the day. That's not counting the cost of the driver, and assuming bus capex is efficient. So even a commute-sharing system like that being tested in Waze would be more efficient than busses.
    - erispoe 10y ago
      The bus is only "underutilized much of the day" in low density areas where automated on-demand cars would make sense. In cities like San Francisco or New York, or even Los Angeles, buses are relatively full even in the middle of the day. Buses take as much space as 3 cars. Even if you can manage to optimize everything perfectly to pack 4 people in these cars at all time, you only move 12 people using the same amount of road of a bus transporting 60 to 90 people, much more in articulated vehicles. There is just not enough room in dense cities. You have to consider the overall efficiency of a bus network, not one particular trip. In urban centers where buses are run on frequency, not timetable, a transit line is attractive because it runs often. People take the bus in rush hours in part because they know they can depend on it all day. These seemingly low-efficiency trips where the bus is half empty are actually very important to the overall efficiency of the network, because they induce demand. The case for transit is a space argument, not a fuel argument. Mass transit is simply the most space efficient way of moving people around.

by erispoe 10y ago

Zigurd 10y ago

Automated vehicles will come in a range of sizes, from 2-seat pods to, at least, mini-bus sizes. Currently we have about the worst utilization of vehicles possible. Drivers drive alone, and park their cars for long intervals. This is why one can claim that trains move enough people to fill 20 car lanes. At the other end of the spectrum, diesel busses are noisy, smokey, need a professional driver, and go from underutilized to packed, depending on time of day. A mix of automated vehicles will be able to much more closely approach optimal load factors at all times of day. 6 or 8 passengers can ride in a car-sized automated vehicle. That makes streets a lo-capex alternative to rail.

erispoe 10y ago
With bigger vehicles, it becomes very impractical to not run them on a fixed route. Pairing people together works well enough, given enough demand, on UberPool and Lyft Line, it's inefficient for the bus sized vehicles you need to use street space efficiently. You need to pair routes while maintaining an acceptable waiting time. Automated or not, mass transit is just geometrically way more efficient, there's no way around it in dense urban environments. Your argument might be valid for a mid-sized american city, or a suburb, but it doesn't work for a european city, or even a dense american downtown.
- Zigurd 10y ago
  > Automated or not, mass transit is just geometrically way more efficient Actually diesel busses are only "efficient" when they are full. They're barely as efficient as single occupant cars just on fuel use when you factor in the bus running underutilized much of the day. That's not counting the cost of the driver, and assuming bus capex is efficient. So even a commute-sharing system like that being tested in Waze would be more efficient than busses.
  - erispoe 10y ago
    The bus is only "underutilized much of the day" in low density areas where automated on-demand cars would make sense. In cities like San Francisco or New York, or even Los Angeles, buses are relatively full even in the middle of the day. Buses take as much space as 3 cars. Even if you can manage to optimize everything perfectly to pack 4 people in these cars at all time, you only move 12 people using the same amount of road of a bus transporting 60 to 90 people, much more in articulated vehicles. There is just not enough room in dense cities. You have to consider the overall efficiency of a bus network, not one particular trip. In urban centers where buses are run on frequency, not timetable, a transit line is attractive because it runs often. People take the bus in rush hours in part because they know they can depend on it all day. These seemingly low-efficiency trips where the bus is half empty are actually very important to the overall efficiency of the network, because they induce demand. The case for transit is a space argument, not a fuel argument. Mass transit is simply the most space efficient way of moving people around.