Monorails have been around since the 1800s, but only really came to public attention in the 1950s when Walt Disney installed one in his new theme park: Disneyland, California. In most parts of the world their use is still restricted to amusement parks, however in Asia – particularly Japan – they also play an important role in public transport around major metropolises.
Modern monorails are based on a single solid beam that supports and guides the train; the carriages are either suspended beneath the track, or sit on top, with their wheels straddling electricity, which is carried on a ‘third rail’ either within, or connected to, the main beam. Conductive shoes on the carriages then transmit the current to the train.
The straddle-beam design is the most widely used. The carriages have pneumatic rubber tyres, which drive along the top of an ‘I’-shaped beam. To prevent side-to-side swaying of the train, a series of smaller tyres clamp around the beam, providing general stability and also helping to guide the carriages.
Suspended monorails, meanwhile, hang underneath the track. The design can be a where the cars hang from the underside of the ‘I’ beam, or alternatively the wheels can sit inside a hollow steel girder. In the latter case, the wheels are completely enclosed, protecting them from the elements and making the train extremely difficult to derail.
In fact, monorails are one of the safest forms of transport. The elevated track minimises interaction with traffic and pedestrians, eliminating the need for crossings, and derailment is very rare. They are energy efficient too and their rubber tyres produce the beam. They are usually powered by simple inversion of the straddle monorail, much less noise pollution than the metal wheels of conventional trains.