Last week we discussed why the Staten Island Economic Development Corporation’s idea for an Aerial Tram connecting the island borough to the southern tip of Manhattan was, like, a really, really terrible idea.
Five days ago, meanwhile, major manufacturers Leitner-Poma and Doppelmayr admitted that such technology doesn’t even exist yet to make the system viable. “The technology for a tram to do this distance isn’t yet there,” stated Tom Sanford, vice president of sales for Doppelmayr.
I’m sure this is going to confuse people.
Given long-distance gondolas over water in Vietnam and 3S cable cars crossing for miles over British Columbia mountain valleys why is it not possible to cross 5.7 miles of inner New York harbour?
The answer is straightforward for industry insiders, but totally confusing to the general layman. Note what Sanford said — “the technology for a tram to do this distance isn’t there yet.” The operative word is tram. As in Aerial Tram.
For outsiders, the cable car sector is completely baffling. In our experience, most people assume that all cable cars are the same. In their world, buses are all basically identical just as are all streetcars and subways.
The thing about cable cars is that they are not a single, unified technology. They’re not all the same. Cable cars are a family of technologies with significant nuances between them. Those nuances affect the viability and cost-benefit of any given project and should be understood—at least superficially—by project proponents before going public with any idea.
So now we have a classic case of a major government agency spending a significant amount of public time and resources to conceive a project that is completely without merit. Somehow they even managed to come up with a cost estimate of $175 million USD to build something that the builders have publicly stated cannot be built. And that happened because the proponents didn’t so much as understand the basic performance characteristics of an Aerial Tram. Had they understood those characteristics, they’d have known this project was dead from the beginning.
Lesson — know your technologies and match the right technology to the right project. That doesn’t apply just to cable cars, it applies to all transit planning endeavours.
Want to learn more about the difference between Aerial Trams and Gondolas? Read our post Aerial Trams vs. Gondolas.
14 Comments
True : the actual technologies are simply not fit to this scenery for several reasons, one not cited in your exceptionally well thought analysis , is that in an horizontal line of such length , the weight of traction cables will surpass -even greatly- the weight of load transported.
But this doesn’t mean that is impossible , it needs a step-up on technologies.
I work at Jackson Hole Mountain Resort. Yes, that’t our 100-passenger tram on the first page of the SIEDC’s PowerPoint. We run both our tram and gondola year-round and I can confirm almost nobody knows the difference between a tram and gondola. The terms ski lift, chairlift, tram, gondola and cable car are completely interchangeable to the general population. I am also constantly surprised how terrified non-skiers are of these machines after driving hundreds of miles on two-lane roads to get here!
I always find that highly amusing, too. People who will drive to work every day and take an elevator 40 stories into the air never realize that an elevator and a cable car are basically the same technology.
But does the technology exist for a gondola? I couldn’t find the alignment and it does sound like some adjustments are needed in alignment but could a 3S system do this? By my calculations it would only be marginally slower at about 18 min for the crossing. Obviously that would mean a big step up in capacity. What do you guys think? Could even a 3S pull this off?
I’m reasonably certain that a 3S system could pull this off. There’s a new system in Vietnam that’s under construction that’ll be the longest 3S in the world. I believe it’s the Fansipan system (though don’t quote me on it) and that’ll be 7km long (4.35 miles). So do I think it’s possible? Sure, why not. That doesn’t change, however, the issues of building towers/pylons in the middle of the shipping lane nor the aesthetic issues with crossing in front of the Statue of Liberty. I think it would be more logical to find a more circuitous route via New Jersey that eliminates those problems and increases service area coverage.
To be viable and sustenable a connector that spans over 6 or 8 kms needs :
– an average speed on line of 14 m/s – 50 kmh
– Multiple cabins of 100 places each – half of this seated
– Dwell times > 3′ – 42 cabins total = 2000 pphpd
– Dwell times > 2′ – 3000 pphd
Double cabin dimensions up to 200 places = 6000 pphd
Time of the trip <10'
Wind resistance up to 100 kmh
Actually this is out of the actual technological possibilities of a 3S or Funitel , apart the wind , where Funitels are certified for service until 120 kmh windspeed.
But this doesn't mean that is impossible to achieve , after all, moving 3000 people in an hour correspond very roughly to a 360 tons/hour debit , a feat already done in the past
Need an evolution though , an 8500 metres ø50 mm haul rope will weight more than 160 tons alone.
Giorgio, why don’t you think a 3S can do this? It can handle 100 km/hr winds, and can easily hit 3,000 pphpd. Sure it wouldn’t be 14 m/s, but even at 8.5-9.0 m/s the journey time would be around 15 minutes. Meanwhile, using a 3S you’d be able to much shorter wait times between vehicles.
I’m talking theoretically, of course. It’s still a bad idea because of all the towers in the water and the view of the Statue of Liberty issue.
Sorry, post lost my formattation and now is nearly unintelligible
I’m just lovin’ the comment count – Shouty Steve gets ’em started!
Is that a good thing or a bad thing?
Its about tensile strength and weight per metre for the pulling cable. If the length is too long the cable will has not enough strength to overcome its own rolling/friction resistance. Once that point is reached it doesn’t help to make a thicker cable as it will have a higher weight. The problem could be lessened if both station have drives but this will need some kind of syncing the motors. There were very long gondolas for transporting bulk material. But the had many short cable loops with intermediate stations.
As much as I like cable propelled systems. For very long horizontal lines self propelled vehicles are the better choice. The still could be suspended from cables.
Here’s the perfect technology then! https://en.wikipedia.org/wiki/Aerobus
Aerobus lose one of the biggest advantages of cable transport: the climbing ability
Aerobus would be suited for this application. There are no steep gradients when crossing water. Gerhard Müller which invented the Aerobus was also the inventor of the Monocable Gondola as he invented the Müller Clamp. So he knew very well about the benefits and disadvantages of gondola systems.
Unfortunately there was never a large Aerobus system. And as of know i doubt anyone will be able to build such a system.