A standard
propulsion cable (or ‘rope’) is not uniform in diameter. The basic nature of taking dozens of separate, uniformly-shaped strands and
winding them together into a larger rope ensures non-uniformity. That non-uniformity has three major drawbacks:
Firstly, the ropes wear more heavily on rubber components such as the sheaves and bullwheels than they would were they of a uniform diameter.
Secondly, the lack of uniformity causes slight vibrations between the ropes and other components that cause an increase in noise. The low-level humming one hears at a ski lift is typically due to this issue.
Thirdly, increased rope maintenance is required than would be necessary with ropes of uniform diameter.
Cables such as Fatzer’s
Integra (Steel) line of ropes are almost completely uniform in diameter, but that uniformity results in a rigidity that prohibits their use as propulsion ropes. Such uniform-diameter ropes can be used almost exclusively for
support functions (such as in a
3S or
Aerial Tram installation).
What the Performa line of cables does – in layman’s terms – is fill in the ‘gaps’ of a rope’s diameter using plastic to best-approximate a uniform diameter. The flexibility of the plastic, meanwhile, allows the rope to be used as a propulsion cable.
That benefit, however, comes at a cost. A Performa rope costs roughly twice the price of a standard rope. That premium feature is often out of the price range of most ski hills as: a) hills only experience a short 4 month long peak season; b) lifts typically operate for only 8 or 9 hours out of the day and; c) the outlying areas ski hills service minimize the need for decreased noise pollution.
But here’s the interesting thing: On a typical lift, the rope costs less than 1% of the total project price. So while a rope such as the Performa may be cost prohibitive in a ski lift market, the marginal cost of a Performa cable is more than justified in the urban market. This is due simply to higher overall project prices in urban installations; the need for decreased noise in urban environments and; the need for decreased wear-and-tear on a system due to increased overall usage in urban markets.
In other words, ropes such as the Performa should yield significantly greater benefits in an urban environment as compared to the marginal costs involved in their application.
It’s common to hear complaints from people about the aforementioned low-level humming of lifts as an argument against their application in urban environments. Yet here we have, again, a tried-and-tested method of dealing with that very problem. But since the cable industry is still focused on their core ski lift market, this solution is rarely offered
proactively as a solution to laymen in the urban transportation industry.