from Hacker News

Why Nonstop Travel in Personal Pods Has yet to Take Off

by larubbio on 9/25/15, 2:29 PM with 75 comments

• by 1024core on 9/25/15, 4:49 PM

  Having taken MUNI (SF's light rail) underground in SF, I have some doubt about the efficiency of such a system. In my station (Church), in the morning, I can see trains coming in every 3-4 minutes or so; and about 40 people get on at once. With a PRT system, you'd have to first line up at the turnstile to punch in your destination. Assume 15 seconds each. Then, when a car comes in, you'd have line up to get in. A person gets in, swipes her card, punches in the destination, etc. Minimum time: 1 minute, if you're being fast. Suddenly, the bandwidth is just not there; the platform becomes the bottleneck. Same would happen at an elevated pathway too, I imagine.

  So, a system like this would be infeasible in a dense city like SF. Above ground is another story altogether: the NIMBYs would block all construction.

  What could work is a system of autonomous vehicles (taxis) the size of a Google self-driving car, running above ground, summoned via a smartphone app or a kiosk at every corner. So, instead of dedicated pathways and elevated tracks, use autonomous cars.

  Also: very importantly, each car must have odor detectors / biohazard detectors in case someone has an 'accident' in the car.

• by rm_-rf_slash on 9/25/15, 4:27 PM

  Here in Ithaca, NY, we have three major communities that are relatively close, but just too far away from a combination of distance, elevation from hills, and miserably cold temperatures: downtown, Ithaca College, and (Cornell's) collegetown. A simple pod connection between collegetown and downtown, and then another route to IC, would do wonders for our transit system.

  See, the nice and terrible thing about Ithaca is that it's a small valley hemmed in by hills on three sites and a lake to the north, so most things tend to be bunched together, which can be almost walkable, depending on distance, temperature, and whether you're carrying groceries. The downside is that there are like 5 arterial roads to get anywhere meaningful in the area, and if just one of them is closed for construction, traffic slows to a halt.

  We don't need long or complex routes. I've been on the WVU pods, and while they're nice, they go FAR. I'm talking about a quarter or less of the distance they cover, and only in two directions (and maybe a third because you have a better chance of getting into Willy Wonka's chocolate factory than finding parking at the farmers market). So please, by all means, if you're looking to trial travel pods somewhere, start here.

• by tkinom on 9/25/15, 4:36 PM

  They might want to try these approach:

  1. They should convince company with $$$ such as Google, FB, Apple to build this for building between their campus buildings.

     Those company has $ and regulation issues might be might a lot smaller compare to convincing a city like SF to do it.
  
     Might be easier to sell because of the "cool factor". 
  
     Those companies can easily convince City of Mountain View, Sunnyvale, Cupertino to let them do it.
  
  

  2. If #1 works, those companies can build routes between the public transit hub, large shopping malls to company. Help ease the parking/commute issues.

  3. Convince Disney Land, World to do this for the "cool factor".

  4. All Major convention centers, sport stadium to build routes to major shopping mall/large parking structures nearby.

• by martythemaniak on 9/25/15, 4:39 PM

  I've been thinking about this a lot and think there's a few things to think about.

  First, the reason we haven't seen these is because until very recently the tech needed to make them cheap wasn't there.

  Second, the technology seems to be caught a classic "worse is better" situation. The actual PRT tech is clearly superior to buses and LRTs, but those are well understood and there's a simple evolutionary path (car, bus, bus lane, lrt, lrt lane, subway). PRTs require a leap of thinking from people and governments don't have any incentives or mandate to take such risks.

  Third, PRTs tracks may be hard to connect to a true network where pods seamlessly switch between tracks.

  Finally, the self driving car could very well kill this in its tracks, but no form of transport can deliver speed or consistency without a dedicated right of way, be that suspended track, tunnel, marked lane etc.

• by jerf on 9/25/15, 4:38 PM

  It's just too far ahead of its time. You need to be able to do this without building special infrastructure for the pods, which is an enormous risky up-front investment for something that is, frankly, almost certain to fail. Times will change and the infrastructure can't change with it. And you can't roll the system out a little bit and get a little bit of the benefits; it's useless until you fully cover a significant set of use cases.

  By contrast, if the pods were self-driving cars on the roads that already exist, the economics change completely. No special infrastructure. Can easily roll out on a small scale for small benefits. Can easily ramp up. Massively smaller initial outlay. System can grow and pay for itself as it goes.

• by jpollock on 9/25/15, 5:22 PM

  This type of system would seem to have the same failure modes that complex baggage handling systems have. [1]

  They are both moving baggage (passengers) on demand between two points. I seem to remember seeing an article indicating that the failures Denver was having (all the empty pods end up at one spot) was visible in experiment, but I can't find it now.

  [1] http://www5.in.tum.de/~huckle/DIABaggage.pdf [2] http://cdn.intechopen.com/pdfs-wm/630.pdf

• by listic on 9/25/15, 5:35 PM

  London Heathrow Airport has Travel Pods like that: https://youtu.be/F5Knmgr2Ge8

  Wikipedia article lists five operational systems like this in the world: https://en.wikipedia.org/wiki/Personal_rapid_transit#List_of...

• by rch on 9/25/15, 4:43 PM

  I'm surprised ULTra wasn't mentioned:

  https://en.wikipedia.org/wiki/ULTra_(rapid_transit)

• by fit2rule on 9/25/15, 5:32 PM

  What I sometimes wonder about is whether or not we'll some day seen these kind of personal pods configured for use on existing railway stock. Many times while waiting for a train, I've sat there pondering - "what if I could build some sort of portable segway-like thing that I could just clamp onto one of those rails on the track, step onto it, and propel myself down the line" .. and I honestly can't think of any major reasons why this wouldn't be viable in this day and age. Pods could clamp onto the existing rail, shuttle individuals around, communicate with each other to avoid collisions, and so on .. maybe I'm just not thinking it through well enough, but couldn't we just build better rail-transport devices at the personal level which utilize the existing infrastructure, instead of having to rebuild it all from scratch with incompatible systems?

  Something like this, only better:

  https://www.youtube.com/watch?v=8YVVSzS3Fco

• by joe_the_user on 9/25/15, 6:24 PM

  This sort of thing was tried and apparent failed in the planned "ecotopia" of Masdar City.

  "The initial design banned automobiles, as travel will be accomplished via public mass transit and personal rapid transit (PRT) systems, with existing road and railways connecting to other locations outside the city..."

  But "Under a revised design, public transport within the city will rely on methods other than the PRTs."

  Reference: https://en.wikipedia.org/wiki/Masdar_City#Transport_system

• by JDDunn9 on 9/25/15, 5:13 PM

  I don't think you can argue that self-driving cars killed PRT, when we are still building brand new subways and light rail.

  I think anything new/innovative loses in the sound byte war. I remember ~2 years ago, the election for mayor of Honolulu hinged on the candidates' stances on building a railroad vs. expanding the existing bus system (rail won). I think if either of them were arguing for PRT, you couldn't explain it to voters in the sound bytes summaries the news gives us.

• by beefman on 9/25/15, 7:03 PM

  Didn't Aaron Patzer explain this, back when he concluded that Swift PRT wouldn't work?

  https://web.archive.org/web/20140723180502/http://swiftprt.c...

• by jchoong on 9/25/15, 5:34 PM

  This has a great (and updated) set of links for all PRT efforts http://faculty.washington.edu/jbs/itrans/prtquick.htm

• by peter303 on 9/25/15, 6:23 PM

  I would think tracked PRTs would need less road space than driven cars. In medium density cities roads are a quarter of square footage. You could probably take out 1/2 or 2/3rds existing roads then and convert them to yards or parks.