The San Francisco Cable Car

One of the enduring images of San Francisco is that of a cable car traversing the hills (with the bay in the background). The cable cars remain one of the largest tourist attractions, and are continued to be used by the locals (though certainly not for its speed). It is also a brilliant piece of engineering, something I only began to comprehend once I went to the Cable Car Museum, which also doubles up as the storage, maintenance and central operations of the entire cable car.

Wikipedia would be better to understand the whole system, but here is the gist. Traditional cable cars, have a rope slung between two points with a carriage dangling below. The rope moves, dragging the car along. String the cable between a high point and a low point, and you get the cable car as seen on Table mountain and elsewhere.

Instead of overhanging cables, the cables in the SF system run under the streets, with centralised controls. The cables run constantly (you can hear them run) and the cable cars have a mechanism to "grip" and release the cable. When it grips the cable, it moves forward, when it is released it stops. There are two key advantages of the system, which are only now overcome with modern cars - they can climb very steep hills and even stop on hills & they effective travel at a constant speed regardless of the incline.

They are no longer the most practical means of transportation, but they do their job well. They are expensive ($6 each way) but the passes are also valid on the system, and this makes it a lot cheaper.

(Clicking on a photo will enlarge it slightly)