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Please don't editorialize the title. The original title is actually "Basics: Technology Never Changes Geometry." The OP's main point is that in dense urban are
by cs702 3y ago
Please don't editorialize the title. The original title is actually "Basics: Technology Never Changes Geometry."
The OP's main point is that in dense urban areas, replacing high-capacity vehicles with small-capacity ones presents a geometric challenge, because the surface area covered by streets is fixed. Were we to replace every bus carrying an average of, say, 40 people, with 20 small self-driving vehicles, each carrying an average of two people, the street surface area occupied by the small vehicles will be significantly greater and traffic will slow down to a crawl. Imagine a gazillion small vehicles stopping everywhere to pick up and drop off passengers. As the OP correctly points out, finding ways to use space efficiently is the core problem of urban transportation.
- Phil_Latio 3y agoThe additional vehicles could simply drive around the "hot" zones...
- quantumwannabe 3y agoThe author forgot about time. 20 small self-driving vehicles that come every 30 seconds uses no more road space than a 40-person bus that comes every 10 minutes. Musk's self-driving taxi idea also isn't new. It's essentially the same thing as Personal Rapid Transit [1] which was originally envisioned back in the 1950s as a way to solve real world public transit system issues: >Most mass transit systems move people in groups over scheduled routes. This has inherent inefficiencies. For passengers, time is wasted by waiting for the next vehicle to arrive, indirect routes to their destination, stopping for passengers with other destinations, and often confusing or inconsistent schedules. Slowing and accelerating large weights can undermine public transport's benefit to the environment while slowing other traffic. >Personal rapid transit systems attempt to eliminate these wastes by moving small groups nonstop in automated vehicles on fixed tracks. Passengers can ideally board a pod immediately upon arriving at a station, and can – with a sufficiently extensive network of tracks – take relatively direct routes to their destination without stops [1] https://en.wikipedia.org/wiki/Personal_rapid_transit https://en.wikipedia.org/wiki/Personal_rapid_transit
- jcranmer 3y agoAnd if you look at the history of PRT systems, they haven't been terribly successful. It's not a new technology--it's 50 years old--and yet there are still so few examples of its employment.
- kalverra 3y agoI went to WVU where we have still actively use the PRT system built in the 70s. It's the school's main system of transport, and when it worked, it was pretty great. When I was there, it was infamously unreliable, but supposedly that's improved a lot lately. I do often miss it, and wonder why more places don't implement something similar.
- caditinpiscinam 3y agoI don't understand your point about time; how does 20 small vehicles not take up more room than a bus?
- quantumwannabe 3y agoThe bus and the 20 AVs have the same throughput (40 passengers in 10 minutes). While the AVs take up more physical space than the bus, they require the same amount of road space to transport the same number of passengers in the same amount of time. You have to have extremely short bus headways before the road space efficiency tilts back towards its favor.
- yongjik 3y agoSeems like you're basically saying "It doesn't matter because the same road can support either a bus or 20 cars." (1) This is a bad metric because it means everything is equivalent until traffic jam occurs. (Why stop at 20 cars? How about 2,000 cars?) (2) More importantly, everything cannot be equivalent because traffic jams do occur in any respectably-sized city. Having 20 cars instead of one bus absolutely does contribute to having more frequent and severe traffic jams.