A couple days ago a reader sent us a link to a proposed aerial PRT transit system called the SkyTran.
At first glance, it looks kinda cool and sorta stands out from some of its PRT counterparts — its got a slick futuristic vehicle design; it’s suspended on lightweight tracks and it was co-developed by a very credible organization, NASA’s Ames Research Centre.
SkyTrans conceptual vehicles and station design. Image from SkyTrans.
And unlike some other conceptual PRT systems, there’s even better news — it might actually get built! Tel Aviv announced its intentions to be the first city to construct a fully functional line by 2014!
This got me thinking, maybe those genius scientists at NASA finally figured out a way to solve mass transit and traffic gridlock! Amazing! Right?!
Well unfortunately the initial excitement kinda wears off quickly when you realize that a functioning prototype has yet to be built — even though the concept was proposed over 20 years ago. Now this is not atypical of new transit technologies, but when you start analyzing the numbers and proposals, the SkyTran really starts to look like another one of those pie in the sky ideas.
The SkyTran makes similar claims found in almost all other “revolutionary” transport technologies, you know — high safety, quick travel times, low implementation costs, quick construction times, high sustainability and etc etc.
Some of the basic stats I’ve been able to find online are:
- Maximum speed: 150km/h (though SkyTran admits it will be much slower during initial operations)
- Cost: ~$8 million/km
- Station spacing: 400m
- Vehicle capacity: 2 persons per pod
- Energy usage: Neutral, once solar panels installed on guideways
Now based off these numbers, there doesn’t seem that there’s anything particularly exceptional — except maybe the energy neutrality part. But perhaps the most unimpressive thing is that the 2 person capacity pods basically means that line capacities will probably be so low that it won’t make much of a difference — unless you build dozens of these lines.
And maybe whats even worse, passengers aren’t even afforded the opportunity to have a meaningful face-to-face conversation. Image from SkyTran.
And here is where the concept breaks down for me (there are other aspects but I won’t go into them for brevity reasons): they claim the system will operate like a taxi! And this statement was made after proposing a $50 million, 6.4km network in Tel Aviv that only connects Atidim Park and Tel Aviv University.
So in other words, unless the City spends hundreds of millions of dollars on criss-crossing Tel Aviv with whole bunch of SkyTran lines, you’re essentially left with an incredibly expensive yet poorly connected aerial taxi.
And at this point, it makes you wonder. What’s the point in installing something like this when Nissan just announced their intentions of introducing the world’s first self-driving cars in just 7 years. And that’s not even the best part: Nissan estimates that they can transform your regular car into an autonomous one for a bank-breaking $1000.
Now you be the judge: $50 million for a shiny elevated SkyTran line? Or maybe just automate 50,000 taxis/cars to improve traffic flow?
I know which one I’d choose.
11 Comments
I did some simple math and found (as always with PRT) that the person/hour capability is very low, but even this is not THE problem , the main plus of PRT is the possibility of choice of destination and time, so we need a grid-like network or branched tree, with a PRT Pod always nearly avalaible .
Transport this in a real world, where people transport necessities are dictated by work and school times , and thus with a heavy imbalance of flows.
To make it work in a real world, you need : to garage your pod at your home and workplace , or to have an enormous number of vehicle that have to run empty…
Go figure the efficiency ….
Giorgio: Agreed. I just don’t think the math works out here.
might b cool for the initial ride but definitely a white elephant if built. hopefully officials in tel aviv aren’t trying to fulfill some sort of sci-fi fantasy
I think this is Tel Aviv’s better idea, extensive bikeshare – https://www.tel-o-fun.co.il/en/
They should scrap the PRT nonsense and spend the money on improving bike lane connectivity. See a map of the current extent here: https://www.tel-o-fun.co.il/Portals/2/shvil_ofan_Eng.pdf
Question for the GP readers out there? What would be the cost for an aerial gondola on the same route and how does it compare cost wise, and capacity wise?
Matt: What are we talking about? PRT vs. bikes or PRT vs. Cable Cars?
There where gondolas for just two person, sitting face to face. The two i have ridden as a child (Braunwald and Davos, both in swizerland) where dismantled and replaced with a higher capacity gondola.
Bear in mind that in alpine resorts almost 100% of the gondolas going downhill are empty. In a city we will have a better ratio. And be it PRT and gondola since the vehicle are light, efficient and don’t need drivers it doesn’t matter much if the have inbalanced loads. all other means of transportation have the same problems. Cars need huge parking spaces. So it might be better to have some empty circulation than parking the vehicles for 22h a day.
The real issue is when vehicles have to merge into a line this is the main cause of traffic jams. All high capacity urban rail systems are line haul system for this reason. So i high capacity PRT will be just like a gonodola just with self powered vehicles.
A solar powered skilift already exist, even in winter it produces more energy than it uses.
PRT idea definitely has to go. Automated cars is essentially PRT if you decide not to own the vehicle you’re sitting in. And I’m on the fence about bikeshare still. I think there needs to be a coordinated effort to install bikeshare and add more dedicated bike lanes at the same time. One without the other makes it hard to convince more ppl to bike. Tel Aviv’s proposed bikeshare network looks interesting. Not sure about cost, but network looks quite extensive. Hard to make a direct cost comparison as the two modes serve different purposes…
Nick,
Tel Aviv’s bike share is not proposed. It already exists.
It’s city wide so is one of the most extensive in the world.
Yes Steven, I meant PRT vs cable car.
You missed the biggest lie in the Skytran story.
All NASA has done is rent the promoters empty space.
Woogy,
Do you have a reference for that claim?