Rubber-tired metro

Rubber-tired metro is an intermediate form between rail and road transport: the vehicles have wheels with rubber tires like a bus, but as a road it uses a set of two parallel concrete rollways, each with the width of a tire. Like on a railway the driver does not have to steer (which would be very difficult on such a 'road'), because the vehicle has additional horizontal wheels, also with rubber tires, rolling along vertical guide bars on both sides of the track.

On some systems, between the rollways there is a regular railway track and the vehicles additionally have classic metal rail wheels, but these are normally at some distance above the rails and hence not used; they take over in the case of a flat tire. Other systems have other sorts of flat tire compensation methods.

The vehicle is electric, with power supplied by one of the guide bars, which thus also serves as the third rail (the current is not picked up through the horizontal wheels, but through a lateral pickup shoe). The return current passes through a return shoe to one of the rails, or to another guidebar depending on the type of system.

The advantages of rubber-tired metro systems include quietness of operation and ease of climbing slopes. The latter can improve efficiency because the tunnel can be built in a basin-shaped profile between stations, allowing the trains to use the down slope to accelerate from rest and the upslope to decelerate as is the case in Montreal.

Rubber-tired metro was first applied to the Paris Metro, when line 11 was converted in 1956, followed by 1, 4 and 6. Because of the high cost of conversion this is no longer done in Paris, nor elsewhere; now rubber-tired metro is applied for new systems or lines only, including line 14 in Paris.

The first completely rubber-tired metro system was built in Montreal, Canada; see Montreal metro.

Here are some cities that have at least partly rubber-tired metro systems:

Canada:

• Montreal

Chile:

• Santiago

France:

• Lille
• Lyon
• Marseille
• Paris
• Toulouse

Mexico:

• Mexico City
• Monterrey

A rubber-tired tram connects central Tokyo, Japan with the Tokyo harbour area.