Look, Up in the Sky!

Aerial Trams, technically known as aerial ropeways, have been around for centuries. In ancient India and Japan, ropeways were used to cross rivers and were originally made of hemp or rawhide rope. Today’s ropeways are made from steel cables and towers, but their function is not much different from these original ancient transportation systems.

Aerial ropeways are a fixed guideway transit mode that moves people by suspending them in a cabin and transporting them with a rope held up by towers. There are four major parts to a ropeway; ropes, towers, terminals, and cabins. The configuration of these parts leads to the different types of urban ropeways including reversible, gondolas and bicable/tricable ropeways. Reversible ropeways use two ropes, one to pull and another to provide stability. The carriage and arm of the cabin run on wheels back and forth on the same side. This is different from Gondolas, which grip a single rope that rotates around wheels at the terminals with the cabin attached. Most of the ropeways in the United States are ski lifts; however, three American ropeways are currently being used for urban transport. They are New York City, Portland, Oregon and Telluride, Colorado.

Ropeways are not for every transit situation. Research done at West Virginia University suggests that the technology is most successful when there is a significant physical obstacle that precludes other transit or transportation types. Mountains, rivers, and freeways are just some of the obstacles currently surmounted by aerial trams. Ropeways are also limited by the technology to a direct point-to-point route. This may preclude expansions or stops along the way.

Ropeways work better when there is a great passenger attraction to one end or both ends of an alignment. From the New York City perspective, the Roosevelt Island Tram connects Roosevelt Island to Manhattan. In Portland, the west end of the tram line is Oregon Health Sciences University, the largest employer in Portland. OHSU paid for 85% of the construction costs for the aerial tram because they see it as a critical link for their employees and patients.

The cost of ropeways include construction and operations. The most expensive part of a ropeway is not the ropeway itself but rather the terminals. Portland learned this the hard way when its costs went from an estimated $15 million to $57 million based on a design competition and engineering for a seismic event. Towers are not as expensive, but fluctuations in the cost of steel could change that. Terminals will always be the largest cost however, because they are the largest piece of the ropeway. Gondolas often have a lower cost than reversible ropeways because the longer distances covered by gondolas actually makes them cheaper per mile. Most reversible ropeways are less than a mile while the gondola in Telluride is about 2.5 miles.

Operating costs include maintenance and operations. Labor costs vary by system type- reversible ropeways need operators in each cabin, while gondolas only need attendants at each station. Some savings in operating costs could result from using alternative energy to run the terminal, depending on how much electricity is necessary to drive the bull wheels that drive the ropes. Another issue to consider is insurance. While ropeways are a safe technology, current examples show that insurance premiums can be high.

Aerial trams can be a great addition to an urban transit network if they are able to overcome natural obstacles that might keep a city from connecting its places. As cities grow and are looking for ways to intelligently expand, the aerial tram can be a useful tool for addressing issues of terrain and connectivity