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'Rubber-tyred metro' is a form of rail transport, but using some road technology: the vehicles have wheels with rubber tyres (tires), but using a set of two parallel concrete (e.g. Montreal Metro, Lille Metro, Toulouse Metro, most part of Santiago Metro), H-Shape hot rolled steel (e.g. Paris Métro, Mexico City Metro, the non-underground section of Santiago Metro), or flat steel (e.g. Sapporo) rollways, each the width of a tyre. As on a railway, the driver does not have to steer, because the system relies on a redundant traditional railway system (steel wheels with flanges on steel tracks). However the Sapporo system uses a central guide rail only [1].
Most rubber-tyred trains are purpose-built and designed for the system on which they operate.
Guided buses are sometimes referred to as 'trams on tyres', and compared to rubber-tyred metros. See also Rubber-tyred trams and Bombardier Guided Light Transit.
On some systems (e.g., Paris, Montreal, Mexico City) there is a regular railway track between the rollways and the vehicles also have railway wheels with larger (taller) than normal flanges, but these are normally at some distance above the rails and are used only in the case of a flat tyre and at switches/points and crossings. In Paris these rails were also used to enable mixed traffic with rubber-tyred and steel-wheeled trains using the same track, particularly during conversion from normal railway track. Other systems (e.g. Lille and Toulouse) have other sorts of flat tyre compensation and switching methods.
The vehicle is electric, with power supplied by one, or both, 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 separate lateral pickup shoe). The return current passes through a return shoe to one, or both of the rails, or to the other guide bar, depending on the type of system (as in the case of Lille and Toulouse where there is no conventional track between the guide bars) (VAL)

Contents

Advantages and disadvantages

History

List of rubber-tyred metro systems

Under construction

Planned

References

External links

Advantages and disadvantages

The advantages of rubber-tyred metro systems include a very quiet ride in the open air (as perceived by people outside the train), an extremely smooth ride with usually no jostling around, faster acceleration, shorter breaking distances, and the ability to climb or descend steeper slopes (~gradient 13%) than would be feasible with conventional rail tracks. This ability to climb or descend allowed Montreal's Line 4 to pass under the Saint Lawrence River within a relatively short distance.
However, there are strong disadvantages as well. Rubber tyres have considerably more friction than the optimal combination of steel wheel on rail, thus leading to more energy consumption; another by-product of this friction is a loud roar from the tires which can make conversation difficult in enclosed tunnels. They also rapidly lose their traction advantage under inclement weather (especially snow and ice). Furthermore, it is a more complex technology, using proprietary components, and sharing little standardisation with steel-wheeled systems. Weight advantages are minimal, because the traditional steel wheels and rails are still a part of the system as a safety backup, and are also needed for switching purposes. So, in effect, there are two systems running in parallel. This is more expensive to build, install and maintain.
There is another one in regard to the dissipation of heat: eventually all traction energy consumed by the train — except the electric energy regenerated back into the substation during electrodynamic braking — will end up in losses (mostly heat). Especially in frequently operated tunnels (typical metro operation) this is a widespread problem, necessitating ventilation of the tunnels. By using rubber tyres with their higher energy demand, this problem is even aggravated. Another disadvantage is cost: Rubber tyres have higher wear rates and therefore need more frequent replacement. Although a steel wheels set is more expensive than a pair of tyres, the frequency of their respective replacements makes rubber tyres the more expensive option. And in addition many rubber tyres for guidance will be needed, too.

History

During the World War II German occupation of Paris, the Metro system was used to capacity, with relatively little maintenance performed. At the end of the war, the system was so worn out that thought was given as to how to renovate the system. Rubber-tyred metro technology was first applied to the Paris Métro, developed by Michelin, who provided the tyres and guidance system, in collaboration with Renault, who provided the vehicles. Starting in 1951, an experimental vehicle operated on a test track between Porte des Lilas and Pré Saint Gervais, a section of line not open to the public. Line 11 Châtelet - Mairie des Lilas was the first line to be converted, in 1956, chosen because of its steep grades. This was followed by Line 1 Château de Vincennes - Pont de Neuilly in 1964, and Line 4 Porte d'Orléans - Porte de Clignancourt in 1967, converted because they had the heaviest traffic load of all Paris Métro lines. Finally, Line 6 Charles de Gaulle - Étoile - Nation was converted in 1974 to cut down noise on its many elevated sections. Because of the high cost of converting existing rail-based lines, this is no longer done in Paris, nor elsewhere; now rubber-tyred metros are used in new systems or lines only, including the new Paris Métro Line 14.
The first completely rubber-tyred metro system was built in Montreal, Canada; see Montréal Metro. A few more recent rubber-tyred systems have used automated, driverless trains; one of the first such systems, developed by Matra, opened in 1983 in Lille, and others have since been built in Toulouse and Rennes the first automated rubber-tyred system opened in Kobe (Japan) in February 1981. It is the Portliner linking Sanomiya railway station with Port Island. (Automated driverless systems are not exclusively rubber-tyred; many have since been built using conventional rail technology, such as London's Docklands Light Railway and Vancouver's SkyTrain.) Most monorail manufacturers prefer rubber tyres.

List of rubber-tyred metro systems

Country	City/Region	System	Technology
Canada	Montreal	Montreal Metro	Michelin
Chile	Santiago	Santiago Metro (Lines 1, 2 and 5)	Michelin
France	Laon	Poma 2000	Cable-driven
	Lille	Lille Metro	VAL 206, 208
	Lyon	Lyon Metro (Lines A, B, and D)	Michelin
	Marseille	Marseille Metro	Michelin
	Paris	Paris Métro (Lines 1, 4, 6, 11, and 14)	Michelin
	Paris (Orly)	Orlyval	VAL 206
	Rennes	Rennes Metro	VAL
	Toulouse	Toulouse Metro	VAL
Italy	Turin	Metrotorino	VAL 208
Japan	Kobe	Kobe New Transit
		Port Island Line	Kawasaki
	Hiroshima	Hiroshima Rapid Transit
		Astram Line	Kawasaki / Mitsubishi / Niigata Transys
	Sapporo	Sapporo Subway	Kawasaki
	Tokyo	Yurikamome	Mitsubishi / Niigata Transys / Nippon-Sharyo / Tokyu
Mexico	Mexico City	Mexico City Metro	Michelin
Singapore	N/A	Light Rapid Transit	Bombardier / Mitsubishi
Republic of China	Taipei, Taiwan	Taipei Rapid Transit System (Muzha Line)	VAL 256 (will be replaced by Bombardier's CITYFLO 650 in 2009)
United States	Chicago, Illinois (O'Hare)	Airport Transit System	VAL 256

Under construction

Country	City/Region	System
Switzerland	Lausanne	Lausanne Metro Line m2 (2008)
Republic of China	Taipei, Taiwan	Taipei Rapid Transit System (Neihu Line) (2009)

Planned

Country	City/Region	System
Hong Kong	Hong Kong Island	MTR South Island Line
Republic of Korea	Uijeongbu	one line, name not yet announced (2011)
Macau	N/A	Macau Light Transit System
Turkey	Istanbul	three lines, name not yet announced
	Ankara	one line, name not yet announced

References

★ Bindi, A. & Lefeuvre, D. (1990). ''Le Métro de Paris: Histoire d'hier à demain,'' Rennes: Ouest-France. ISBN 2-7373-0204-8. (''French'')

★ Gaillard, M. (1991). ''Du Madeleine-Bastille à Météor: Histoire des transports Parisiens,'' Amiens: Martelle. ISBN 2-87890-013-8. (''French'')

★ Marc Dufour's "The principle behind the rubber-tired metro". (''English'')

External links

★ TRUCK (bogie)