An aerial tramway is a transportation system consisting of a cabin for freight or passengers suspended from a cable stretched between two stations. Used for transportation up steep inclines or over wide gorges, tramways often operate in tandem, with one cabin traveling in one direction, while a second travels in the opposite direction. A cable called a haulage rope is secured to the cabin itself, which pulls it toward the destination station.
Aerial tramways are ubiquitous in many mountainous regions, especially in those areas where skiing is available. They're not only for tourists, though; one of the critical components of the daily commute for many New Yorkers is the Roosevelt Island Tram, which transports residents of Roosevelt Island directly to Manhattan faster and cheaper than the circuitous bridge and road route through Queens. Portland, Oregon and Medellin, Columbia also operate commuter aerial tramways.
The first aerial tramways were built to move soil and ore, and became popular for mining operations in the western United States in the latter half of the 19th century. By the early 20th century, aerial tramways had become commonplace components of mining operations in mountainous regions worldwide, and became an important method of moving military supplies and equipment during the first world war.
After the first world war, aerial tramways for transporting people first appeared in Europe, especially in the mountains in Switzerland and southern Germany. Less costly to build and operate than the rail systems that had previously been relied on, these tramways were oriented toward the travel and leisure trade. The first aerial tramway in the United States was built for the tourism industry in Franconia, New Hampshire, in 1938, and they proliferated throughout the North American continent after the second world war.
The cables from which tram cabins are suspended are stationery; that is, they're stretched between two locations and don't move. Longer aerial tramways may employ towers along the route to help support the cable. Each set of cables for a tram cabin is called a ropeway, and most aerial tramways build two inter-connected ropeways to accommodate two cabins, one on each ropeway. The cabins are linked by their haulage ropes, so that the weight of the cabin traveling downhill helps pull the other cabin uphill.
Tram cabins have an overhead assembly called a carriage, which contains two or more wheels that ride along the ropeway. The haulage rope is generally secured by means of a clamp to the carriage, and the cabin is pulled uphill by an electric motor in the station. The cabins themselves are built to meet the needs of the system; many cabins are relatively small, holding fewer than 25 people. There are systems with significantly larger cabins, though. A French aerial tramway over the Ponturin gorge employs double-decker tram cabins built for 200 passengers.
In most tourist spots that have one, an aerial tramway itself becomes an attraction in and of itself. Thus, an aerial tramway is a very safe mode of transportation; relatively few accidents have been reported worldwide, though when they do occur, they tend to be very dramatic in nature. Nearly all places worldwide where an aerial tramway might be built have extensive safety regulations in place.