What is Cable Propelled Transit?
Is it safe?
Is it sustainable?
Is cable great for cities?
If cable is so great for cities, why don’t I see it in my city?
So many types of cable transit! What’s the difference?

What is Cable Propelled Transit?

Simply speaking, Cable Propelled Transit (CPT) is a transit technology that moves people in motor-less, engine-less vehicles that are propelled by a steel cable.

The Singapore Cable Car was the first system built across a harbour

Is it safe?

CPT is one of the world’s safest forms of transportation. Research from the Swiss government demonstrates that gondolas and cable cars are safer than all other forms of mass public transit and private automobiles.

Statistically speaking, the chances of a person experiencing a serious injury or fatality while riding a cable lift is remarkably low. On top of an impressive operation record, the industry engineers each system to a high degree of safety, with multiple redundancies and egress options.

All CPT systems are built with one or more back-up diesel engines.

In the extremely rare event of a complete lift failure, emergency procedures are in place with trained crews assisting in the safe and orderly evacuation of passengers.

Is it sustainable?

Gondolas are one of the greenest forms of public transit technologies available. They have a small footprint, operate with electrical motors, generate zero point-source emissions, are whisper quiet, and are highly energy efficient. In fact in some instances, gravity allows a system to generate power. This occurs when the number of people descending on a system outweighs the number ascending.

Is cable great for cities?

When planned, designed, and implemented properly — most definitely.

Cable transit systems are competitive with other medium-capacity systems in numerous cost-benefit categories; can be built in as little as a year; and offer such advantages as less than one minute wait times.

Construction and maintenance costs are often considerably lower than that for other forms of standard fixed link transit thereby making them an ideal feeder for other higher order transit technologies.

Portland Aerial Tram -- CC Image by Flickr user brx0

If cable is so great for cities, why don’t I see it in my city?

That’s a valid point — but it also depends on what city you live in. You can find urban cable systems in such places as:

So many types of cable transit technologies! What’s the difference?

There are two Cable Propelled Transit types: top supported and bottom supported:

Top supported cable technologies are the kind commonly associated with ski lift technology. The most recognized bottom supported cable technologies are funiculars and the iconic San Francisco street car, although there are other technologies which exist.

The major distinction between top and bottom supported systems is how they are supported. Top supported are held up by cables while bottom supported run on rails (in all but the rarest examples).

TOP SUPPORTED: Medellin currently has 3 MDG lines completely integrated into their transit network.

BOTTOM SUPPORTED: The City Center Tram in Las Vegas runs along a set of elevated tracks.

Unlike standard transit vehicles, CPT vehicles do not have an onboard engine or motor. Instead, propulsion is provided by an off-board engine that propels a steel cable. Vehicles are equipped with a grip used to attach the vehicle to the cable. (In the case of a detachable grip system, such as an MDG, BDG, or 3S, the grip is detachable such that the cabins can detach from the cable in the station.)

Depending on the technology, the steel cables can provide only support, only propulsion, or both — this is why some technologies (such as the 3S) have multiple cables.

Between stations cables are kept elevated by a series of towers. Tower sizes and footprints are dependent on cable technology choice, system capacity and tower span distances.

Lighter-weight systems, such as the MDG, typically have smaller, cylindrical towers while heftier systems, such as the 3S, have larger, lattice-style towers. In general, larger tower sizes are correlated to longer tower span distances and larger system capacities.