How does a gondola work? Inside the Christchurch Gondola

How does a gondola work? At heart it is a loop of steel rope stretched between a station at the bottom and a station at the top, held up along the way by towers. A motor in one station turns a large wheel that keeps the rope moving in a continuous circuit, and the cabins ride on it, up one side of the loop and down the other.

The towers do more than hold the rope in the air. Each carries sets of grooved wheels called sheaves, and the operator explains that the sheave assemblies on every tower support the cable and also hold it down.⁶ That second job matters on a hillside, where the rope wants to lift off the towers as the slope changes beneath it.

The cabins themselves are simple. Each hangs from an arm with a grip on the rope. On some systems the grip lets go in the stations so the cabin can creep along a rail while people board, then clamps on again; on others the whole line runs slowly enough to step in and out. On the Christchurch line the operator can briefly stop the ride for anyone who needs help getting in or out, including people in manual wheelchairs.⁷ It is a quiet, steady system, closer to a ski lift than to a train.

A gondola is only as reliable as its towers, and they are serviced on a long cycle. A release from the operator describes a 10-yearly schedule that checks and replaces the main axles and bushes in the sheave assemblies on each tower.⁶ It is slow, careful work on parts that carry the whole load of the line.

The work normally happens out of sight. The same release says it is usually done outside operating hours and often at night.²⁰ During one closure the team used the daylight hours instead, and towers near the summit needed a helicopter to lift the sheave assemblies down for the engineers and fly them back up.¹³

Weather is the other daily factor. Metro warns bus 8 riders that in rough conditions the cabins may stop before closing time or not start at all, and the stop at the base station is then out of use.²¹ On a gusty day, check the operator's updates before you travel, and keep a backup plan in the city.

The earthquake of 22 February 2011 hit close to home: the operator's guide records a magnitude 6.3 quake near Lyttelton at a depth of 5 km that caused 185 deaths.^30,31 At the gondola, RNZ reported that the quake burst sprinkler heads and flooded the building with 60,000 litres of water, and left the surrounding hills dangerous with loose rock.¹¹

Repair meant more than fixing the building. RNZ reported that the building was renovated and the cabins upgraded, with the managing director putting the cost at about NZD 2 million.^32,33 Fences designed to catch falling rocks were built around the gondola buildings.³⁴ A later RNZ report put spending on the fences and renovation at more than NZD 1 million.³⁵

The Christchurch Gondola earthquake closure ran from February 2011 until March 2013.^11,12 RNZ's report of 25 March 2013 says it had reopened that Monday after the long repair.^36,37 The Bridle Path below the cabins stayed closed a little longer while the council cleared hazardous rocks.³⁸

Knowing how the system works makes the ride more interesting. Watch for the towers as you climb, each one carrying its row of sheaves, and notice the gentle bump as your cabin passes over them. At the top, take a moment on the platform to look back down the line you have just climbed.

Plan your timing around the operating rules. Cabins run 10am-5pm daily in summer and 10am-4pm in winter, and you can still ride down for 60 minutes after closing.²² The summit café, history ride and shop close 30 minutes before that last ride.²⁴

If you want to see the machine at work rather than just ride it, stand at the edge of the deck on Level 4, where the cableway drops away toward the valley and the walking tracks start beneath it.²³ From there you can watch cabins pass in both directions and follow the rope down to the base station in Heathcote Valley.⁴³