Lift Blog

The $31 million Jackson Hole Aerial Tram is the most expensive lift ever built at a US ski area.  Constructed by Garaventa over 20 months, the new tram opened to great fanfare on December 20, 2008.  It can move a hundred people 4,083 vertical feet in under nine minutes.  Compared with a detachable lift, the tram is a relatively simple machine built on a massive scale.

Like most jig-back aerial tramways, there are four track ropes and a single haul rope that that drives both cabins.  All five wire ropes were manufactured by Fatzer in Switzerland.  Five towers support the line; towers 1 and 2 are the tallest and furthest apart.  Two CWA Kronos cabins move 650 passengers per hour per direction at a maximum speed of 10 m/s.  Slope length is 12,463 feet.

Because the new, larger tram had to fit into the same footprint as the old tram building in Teton Village, a moving center loading platform takes the place of the upbound car during each trip.  The tram’s gauge gradually widens between towers 1 and 2.  At the top terminal, Garaventa designed four hydraulic gates that drop down and lock the cars into place after they dock.  This prevents cabins from swinging their way into the top dock on windy days.

The tram is powered by twin 1,000 horsepower ABB AC electric motors at the bottom terminal.  The motors are coupled to a Flender gearbox and then the drive bullwheel, which the haul rope wraps around twice.  A 2,400 HP Cummins genset in the motor room and a smaller generator at the summit provide power to run the system normally during a power failure.  If the electric motor(s) fail, a diesel hydrostatic evacuation drive can be coupled to the drive bullwheel.  Another hydrostat with a different coupling system forms a fourth backup.  Each evacuation drive has a remote control that can be brought outside to operate the tram with a view of the line.  A third generator can power tram control in case the grid and primary generator both fail.  Even if none of the four propulsion systems work, each car also has a trained operator and equipment for a rope evacuation.  The original tram had to be rope evacuated twice, most recently in 1996.

The two service brakes and an emergency brake are each tested daily.  Unlike the original, the new tram has no track rope brakes on the carriages.  The haul rope is tensioned by a 220,000 pound counterweight in a pit underneath the top terminal.  Twenty-six slack carriers keep the track ropes and haul rope together over the longer spans from towers 1 through 4.  Every 400-500 hours, cabins 1 and 2 are re-positioned on the haul rope by 10 meters so that the wear points change.

The tram’s electronic controls were designed by Frey AG of Switzerland with components from Siemens and Pilz.  There is no dedicated communications line; rather signals are transmitted through the haul rope including voice communication between the cars and stations.  The entire haul rope is supervised, meaning that if it hits metal at any point along its five mile length, the tram will stop.

The tramway can be operated directly from a console in tram control or remotely by operators in each car.  Tram operators have touch screen controls with the status of the other car and important information.  Each tower has an anemometer which transmits wind speed and direction to the cars and tram control.  During normal operation, acceleration and deceleration are handled automatically.  Tram operators start each trip and always have the authority to change speed for wind or wildlife.

Each car has two batteries which power automatic doors, controls, lights and  the audio system with satellite radio, USB and Bluetooth.  The batteries charge whenever the cars are docked.

The tram is staffed with four full-time mechanics and around a dozen operators each season.  It has accumulated almost 11,700 hours of run time in 67,000 trips to date. Hopefully it will last at least as long as the original tram, which ran from 1966 to 2006.  All five ropes are still original, with the haul rope having been spliced three times to date. The haul rope is expected to last about 15 years while the track ropes will last much longer.