The road not taken: How we found and lost the dream of Personal Rapid Transit

A criticism of PRT systems: [1]

Classic problems:

- Capacity isn't high. One track equals about one freeway lane.

- One broken vehicle stalls the whole track.

- Real guideways are usually much bigger than pictures of proposed guideways. You need emergency walkways, rescue access, and earthquake resistance. This is also true of monorails.

- Somebody has to clean all those vehicles.

Light guideway systems do exist. Intamin, the roller coaster manufacturer, also makes monorails. Theirs are as narrow as roller coaster tracks.[2] Here's their towing and rescue vehicle in action.[3] But their systems are low-capacity and slow. Japan has many monorails with serious passenger capacity, but the guideways are big.[4] One design has a flat guideway that would work for a PRT.

[1] http://www.lightrailnow.org/facts/fa_prt001.htm [2] https://www.youtube.com/watch?v=7HInUerMfWU [3] https://www.youtube.com/watch?v=70q_CoLT3Eo [4] https://www.youtube.com/watch?v=lUpIl25q1nk

Worth noting - a lot of the benefits of PRT are realized with short, one-way on demand car rentals. Obviously you still have to drive, but you get quick access to a vehicle, go where you want, hop out, and someone else gets to use it. At scale it's awesome, but it's been hard for sprawling US cities to get to that scale given entrenched habits.

Here in San Diego I use Car2Go - http://car2go.com/ . It's awesome for stuff like airport runs - I walk to the car (they're about a 5 minute walk from the airport), tap a card on the windshield, drive home (about six bucks and fifteen minutes; cheaper than the bus if my wife is with me), and then when I'm done with it the car is there for someone else to use. They're small, nimble, electric, and fun. Unfortunately they don't seem to be hugely popular since SD is very, very sprawling and their home range is fairly small.

The book on 'Aramis' mentioned is https://en.wikipedia.org/wiki/Aramis,_or_the_Love_of_Technol... ; I picked it up by chance in the room of an anthropology student many years ago and found it fascinating.

It's a sociologist's view of an engineering project management failure, and therefore requires a bit of unfamiliar jargon to interpret. It concerns itself with the question "what is progress and modernity?" quite a bit, as projects like PRT are self-conscious attempts to build a futuristic technology rather than an incrementalist approach of meeting immediate demands.

A slightly different version of this called Bus Rapid Transit is really really successful in the UK and is being rolled out to other cities (Manchester and Bristol). https://en.wikipedia.org/wiki/Cambridgeshire_Guided_Busway

Extremely painful to put in place but once in place hugely beneficial.

The road not taken yet, perhaps? The proposed SkyTran PRT variant has levels of efficiency that are at least in theory way ahead of anything that surface roads and wheeled vehicles can offer. Just as the PRT system highlighted in the story is retained for its genuine value other experiments are likely to tried and retained.

What about variably-autonomous cars? Take a car with self-driving capability and then have it be manually operated while solitary but increasingly self-driving as the group of similarly automated cars it belongs to grows. There's a lot of benefits to group awareness: share sensors, coordinate behavior for efficiency, instant communication, and so on.

This gives us the best of both worlds: safety in numbers, safety in automation and sensors, and it retains the personal autonomy we're used to. All while not requiring 100% perfect autonomous capability.

If the cars were small and cheap enough, they could be made available via subscription (much like a lease) and treated like a municipal transportation network that's superior to light rail and bus networks.

I think this would create problem with monopoly. If city would own and rent out cars, the price would inflate and technology would stagnate. Something like city licensed taxi services.

I wonder if it would be economically feasible to build a modern equivalent of the Morgantown PRT using a standard electric car model (Nissan Leaf, Chevy Bolt, etc.) as the "pods" using nothing but after-market modifications. Such an approach might make sense if new systems like this were dominated by R&D costs -- and, maybe as importantly, R&D schedules.

Here's an idea: what if we built lots of personal rapid transit vehicles, but made them operate on the ordinary cheap-to-build-and-maintain roads that already exist, and sold them outright to the end users so there was no need to maintain a massive centrally controlled network? That could be a game-changer.

I can't help it; every time I read "PRT" I think "Parahuman Response Team".

well self driving cars are being over engineered for the very fact that for very long time if not forever there will always be a manually controlled vehicle along their path.

as for lane set asides, we already have HOV and Express lanes that would easily be adapted to self driving cars, if anything the express lanes would be even more efficient.

Cars like buses always trump trains in metro ranges simply because both can adapt quickly to change of habits. trains might be one solution between cities but even in Europe air travel is supplanting it

Instead we pursued the dream of 140 character messages.

I'm excited about the Hyperloop:

https://en.wikipedia.org/wiki/Hyperloop

http://news.nationalgeographic.com/energy/2016/02/160223-Elo...

http://www.wired.com/2014/12/jumpstartfund-hyperloop-elon-mu...