The Big Wheel.

The article reports on the municipal railway system in San Francisco, California. The railway system runs in a spinning flywheel which works on a principle wherein the weighted wheels serves as a highly useful reservoir of energy. It mentions that engineers use the technology in flywheel for less polluting transportation. It notes that the railway system uses two-third of its energy in climbing the hills of San Francisco which is recovered on the run down. It mentions that Swiss designers have created a flywheel-powered bus called Electrogyro which is used in Europe and Africa