How Do You Cross a Valley With No Bridge? Hang Everything From a Wire

Systems divide into those where one rope does both jobs and those where two ropes divide them. In the single rope arrangement, the cabins hang from a continuously moving loop that both supports and pulls them, which is simple, cheap and limited, since the same rope must be strong enough to carry the load and flexible enough to bend around the drive wheels. In the two rope arrangement, a fixed track rope is stretched between towers and carries the weight while a separate moving haul rope pulls the cabin along it, which allows far heavier cabins, much longer spans between towers and far better resistance to wind, at considerably greater cost.

Several problems recur regardless of the arrangement:

• •Wind, which sways cabins and is the commonest reason for closure
• •Ice accumulating on ropes and shedding onto what is below
• •Rope wear, requiring continuous inspection along the whole length
• •Evacuation of stranded passengers, which must be planned and practised
• •Passing the towers, where the rope is supported on rollers
• •Detaching cabins from the moving rope at stations so they slow for boarding

The most interesting applications are freight and urban transport rather than leisure. Mines and quarries have used aerial ropeways for well over a century to move ore across terrain where a road would be impossible or ruinously expensive, and systems many kilometres long operate continuously with buckets rather than cabins. Forestry uses them to bring timber down slopes. Construction uses temporary ones to supply sites on mountains. And several cities have built them as ordinary public transport, most notably in Colombia and Bolivia, where lines connect steep hillside settlements to city centres, cutting journeys of over an hour to a few minutes and reaching neighbourhoods that buses cannot serve at all.

Several arrangements move vehicles by rope and the differences matter. A funicular runs cars on rails up a slope, connected by a rope over a pulley at the top so that one counterbalances the other, which suits steep ground and carries heavy loads cheaply. A surface lift drags standing skiers along the snow rather than carrying them. A chairlift carries them in the open air on a continuously moving rope. A gondola encloses them. An aerial tramway uses two large cabins shuttling back and forth on fixed track ropes. A rope ferry uses a cable across a river with the current supplying the propulsion. What unites them is a fixed installation doing the work that a vehicle engine does elsewhere.

Regulation in this field has been written largely in response to specific disasters. A collision between an aircraft and a ropeway in Italy in 1998 severed the cable and killed twenty people, which prompted changes to military flight rules over such installations. A fire in a funicular tunnel in Austria in 2000 killed one hundred and fifty five and led to fundamental changes in tunnel ventilation, escape provision and the materials permitted in vehicles. A cabin falling in Italy in 2021 after a haul rope failed, with the emergency brake found to have been deliberately disabled to avoid stoppages, killed fourteen and produced prosecutions and much stricter enforcement of brake systems. The industry is otherwise among the safer forms of transport by distance travelled.

One arrangement uses a single moving loop to support and pull the cabins, which is cheap and limited, while the other stretches a fixed track rope to carry the weight and uses a separate haul rope to move them, which allows heavy cabins and long spans. Wind, ice, rope wear and evacuation are the standing problems. Mines, forestry and several South American cities use them for freight and ordinary transport rather than leisure.