The first use of ropes to transport people was in China in the 16th century. In those days they had to use rope until steel cable was invented in 1834. People used these ropes to cross bodies of water, initially transferring themselves, hand over hand, with the body suspended by a crude harness. The next application was to pull oneself in a basket.
Although Fausto Veranzio of Venice designed a passenger ropeway in 1616, the ropeway industry generally credits Adam Wiebe, a Dutchman, with erecting the first successful operational cable car system in 1644. Cable cars didn't come to America until 1868. The first urban mass transport application of aerial ropeways in the United States was in 1976 with the Roosevelt Island cable car system built in New York City. (It still operates to this day). The first tramway in the United States was completed in 1984 when the city of New Orleans built an Aerial Tram over the Mississippi River for the Louisiana World Exposition.
Cable car systems are an aerial public transit technology in which cabins (also called carriers, vehicles or cars are suspended and propelled from above by cables. The underlying technology of cable cars has been around for almost a century, where it has been applied mostly in terrain-challenged recreational contexts (e.g. Gondolas/Telepheriques in ski resorts) to transport skiers and tourists from the bottom to the top of the mountains and vice versa. In recent years, however, the same technologies that have been used in these resorts have been adopted and implemented in non-alpine urban regions as a mode of urban transit in geographically-constrained urban areas, where conventional transit service was deemed very difficult, or unfeasible to implement.
Cable-Propelled Transit technology (CPT) that also includes rail-supported Cable Cars can be defined as a transit technology that moves people in motor-less, engine-less vehicles that are propelled by a steel cable. In the industrial communities, the term "Ropeway" is used to describe a system that is used for transporting materials and, or passengers in carriers suspended from, or controlled by ropes, or cables, while the term "Aerial Ropeway" refers to any ropeway system that is suspended in the air. The term "Aerial Ropeway Transit" (ART), on the other hand, describes any type of aerial transportation mode in which passengers are transported in a cabin that is suspended and pulled by cables.
Cabins or Carriers
Carriers are defined as the structural and mechanical assemblage in, or on which the passengers of a ropeway system are transported. The carrier includes the carriage or grip, hanger, and the passenger cabin. The carriers can consist of large cabins as in the case of Aerial Tramways, or small and medium cabins as in the case of Gondolas. The carriers are usually described by their capacity (e.g. 80-passenger cabins on an Aerial Tramway system, 15-passenger Gondola etc). The cabins are always totally enclosed and have a standing room to reach full capacity.
Virtually all ART systems have two terminals: a drive terminal and a return (idle) terminal. If a vertical change takes place, the terminals are called the upper and lower terminals. The bull wheel in the drive terminal can operate as the drive wheel, and the bull wheel at the return terminal acts as a fixed return mechanism. For detached grip Gondola operations, a separate area for slow down and loading is needed in the terminals and is often electronically monitored for safety. Some systems that use Gondolas might have few intermediate stations as well to pick up and drop off passengers between the drive and return terminals.
Towers are intermediate structures that support the track and haulage ropes between terminals. They are often steel framed, and are sometimes pylon-shaped. The tower's primary function is to hold and allow the haulage rope movement through wheels. Towers must also have guides to keep carriages from hitting them for safety. Towers might not always be necessary depending on the length of the system. For long systems, intermediate towers are necessary to provide support to the system and therefore eliminating the need for long spans.
The rope (cable) is the heart of any Aerial Ropeway Transit system. The rope is formed by inter-twining individual wires to form a strand, and then the strands to form a rope (cable). There are many variations of the processes used in manufacturing ropes and in choosing the appropriate rope for any given application. One critical point is to specify whether the rope is a haulage rope or a track rope (Aerial Tramways) or if one rope supports both functions (Gondolas). Ropes are generally described by their outside diameter in inches. Other aspects of their manufacturing are not as important. Common usage is a 1 1/8 inch haul rope and a 1 7/8 inch track rope for a Bicable system, or a 1 3/8 inch rope for a Gondola system.
At the present time, ART technologies that have been used as mass transit modes in urban areas include four technologies: Aerial Tramways, Monocable Detachable Gondolas (MDG), Bicable Detachable Gondolas (BDG) and Tricable Detachable Gondolas (TDG).
An Aerial Tramway (also called Reversible Ropeway or Jig-back Ropeway) is a type of aerial lift in which two passenger cabins (vehicles) are suspended from one or more fixed cables (called "track cables") and are pulled by another cable (called a "haulage rope"). The fixed cables provide the support for the cabins, while the haulage rope is solidly connected to the truck (the wheel set that rolls on the track cables) by means of a grip. The haulage rope is usually driven by an electric motor, moving the cabins from one end to the other. The Tramway is sometimes called 'jig back' because the power source and electric engine at the bottom of the line effectively pulls one carrier down using the weight to push the other carrier up. The two passenger cabins are situated at opposite ends of the cable loops. Thus, while one is coming up, the other is going down the mountain, and they pass each other midway on the cable span. Aerial tramways usually have large cabins that can carry between 20 and 200 people at speeds of up to 43 km/h. Depending on the size of the car, line speed, and line length, transport capacities vary between 500 and 2,800 pphpd. Some aerial trams have only one cabin, which lends itself better to systems with small elevation changes along the cable run. The technology is originally developed for ski resorts but was also adopted in other locations as a transit mode. Based on the available information, there are two Aerial Tramway systems that are used as a mass transit mode, both of them in the United Sates: the Portland Aerial Tram and the Roosevelt Island Tramway.
Monocable Detachable Gondolas (MDG)
A Gondola Lift, or as it technically known as Monocable Detachable Gondola (MDG), is a type of aerial lift in which the cabin is suspended from a moving loop of steel cable that is strung between two terminals, sometimes over intermediate supporting towers. The cable is driven by a bullwheel in the terminal, which is connected to an engine or electric motor. Gondolas have small cabins, set at regularly-spaced close intervals. The systems are continuously circulating with cabins passing around the terminal bull-wheels. Cabins detach from the hauling rope at terminals, are decelerated and carried through the unloading and reloading areas at a very slow speed, then accelerated for reattaching to the haulage rope for high speed travel "on the line" between terminals. Cabin capacity of MDG systems varies from 4 to 15 persons per cabin and system capacity can be as much as 4,000 pphpd.
Bicable Detachable Gondolas (BDG)
BDG systems combine features of both Gondola and Reversible Ropeway systems. On the one hand, they use the reversible ropeway technology in their operation (i.e. separate ropes serve the two functions: static support ropes or "track cables" and a moving "haul rope"), which allow the system to have long spans, and therefore overcome difficult terrain conditions. On the other hand, the system is detachable (like Gondolas), which allows the system to have a high capacity similar to the capacity of detachable circulating systems. The difference between a BDG and an MDG system is that unlike MDG systems, which are both propelled and suspended by the same cable, BDG systems have two separate cables for the two functions. Cabin and transport capacities of BDG systems are similar those of MDG systems, with cabin capacities ranging from 4 to 15 persons per cabin and transport capacity of up to 4,000 pphpd. Successful implementations of BDG technology as a transit mode exist in Hong Kong and Singapore.
Tricable Detachable Gondolas (TDG)
Similar to BDG systems, TDG systems (sometimes referred to as 3S technology) combine features of both Gondola and Reversible Ropeway systems (i.e. separate ropes serve the two functions). However, unlike BDG systems, TDG systems have two stationary cables that support the cabins instead of one in BDG systems. Although TDG systems are more expensive than both MDG and BDG systems, this added cost is more than offset by their advantages, as these detachable circulating ropeways can carry more passengers with higher speeds. In fact, TDG systems operate with carrier capacities of up to 38 passengers for a maximum system capacity of 9,000 pphpd. Other advantages of TDG systems include their outstanding wind stability, low power consumption and the use of very long spans of up to 3,000m. Successful implementation of TDG technology as a transit mode exists in the city of Koblenz (Germany).
Other Ropeway Technologies
In addition to the three ART technologies discussed above, there are a few other aerial ropeway technologies produced by the main vendors of ART that are just variations of the basic technologies. These technologies include: Funifors, Funitels and Pulsed-Movement Gondolas.
The Funifor is a relatively new ropeway technology that is mainly used in ski resorts, and has been recently introduced as an ART technology, as will be discussed later. The Funifor is in fact a variation of Aerial Tramways that has two guide ropes and a haul rope 1 loop per cabin. The system consists of two reversible cabins that run on parallel tracks. At the top of each track, the haul rope for that track loops back to the bottom instead of looping over to serve the other track as occurs with a normal Aerial Tramway. This feature allows for single cabin operation when demand warrants. The independent drive also allows for evacuations to occur by means of a bridge connected between the two adjacent cabins. The main advantage of the unifor system is its stability in high wind conditions owing to the horizontal distance between the two guide ropes comprising each track.
Pulsed-movement gondolas are a relatively uncomplicated solution, operating with fixed-grip gondolas running in close sequences like a train. However, since pulse gondolas use fixed grip technology (i.e. non-detachable), this results in slow speeds, long wait times, and low capacity of the whole system, which does not lend itself well for the urban environment. This could explain the fact that pulse gondolas are yet to be used as a mass transit mode in the urban environment. Lagos is a rapidly growing city, currently with over 16m inhabitants. The existing transport infrastructure has become capacity constrained with unacceptable levels of traffic congestion. This congestion results in its inhabitants spending as much as 6 hours per day commuting to/from their place of work, reduced commercial efficiencies which also hamper future economic growth and an overall reduction in the quality of life of its residents.