Light Rail Variations

Light Rail Variations

Trams Operating on Mainline Railways

Around Karlsruhe, Kassel, and Saarbrücken in Germany, dual-voltage light rail trains partly use mainline railroad tracks, sharing these tracks with heavy rail trains.
In the Netherlands, this concept was first applied on the RijnGouweLijn. This allows commuters to ride directly into the city center, rather than taking a mainline train only as far as a central station and then having to change to a tram.
In France, similar tram-trains are planned for Paris, Mulhouse, and Strasbourg, further projects exist. In some cases, tram trains use previously abandoned or lightly used heavy rail lines in addition to or instead of still in use mainline tracks.

Some of the issues involved in such schemes are:

• Compatibility of the safety systems.
• Power supply of the track to the power used by the vehicles (frequently different voltages, rarely third rail vs overhead wires).
• Width of the vehicles to the position of the platforms.
• Height of the platforms.

There is a history of what would now be considered light rail vehicles operating on heavy rail rapid transit tracks in the US, especially in the case of interurban streetcars. Notable examples are Lehigh Valley Transit trains running on the Philadelphia and Western Railroad high-speed third rail line (now the Norristown High-Speed Line).

Such arrangements are almost impossible now, due to the Federal Railroad Administration refusing (for crash safety reasons) to allow non-FRA compliant railcars (i.e., subway and light rail vehicles) to run on the same tracks at the same times as compliant railcars, which includes locomotives and standard railroad passenger and freight equipment.

Notable exceptions in the US are the NJ Transit River Line from Camden to Trenton and Austin's Capital MetroRail, which have received exemptions to the provision that light rail operations occur only during daytime hours and Conrail freight service only at night, with several hours separating one operation from the other. The O-Train Trillium Line in Ottawa also has freight service at certain hours.

Ground-Level Power Supply for Trams

When electric streetcars were introduced in the late 19th century, conduit current collection was one of the first ways of supplying power, but it proved to be much more expensive, complicated, and trouble-prone than overhead wires. When electric street railways became ubiquitous, conduit power was used in those cities that did not permit overhead wires.

In Europe, it was used in London, Paris, Berlin, Marseille, Budapest, and Prague. In the United States, it was used in parts of New York City and Washington, D.C. Third rail technology was investigated for use on the Gold Coast of Australia for the G:link light rail, though power from overhead lines was ultimately utilized for that system.

In the French city of Bordeaux, the tramway network is powered by a third rail in the city center, where the tracks are not always segregated from pedestrians and cars. The third rail (actually two closely spaced rails) is placed in the middle of the track and divided into eight-metre sections, each of which is powered only while it is completely covered by a tram.

This minimizes the risk of a person or animal coming into contact with a live rail. In outer areas, the trams switch to conventional overhead wires. The Bordeaux power system costs about three times as much as a conventional overhead wire system and took 24 months to achieve acceptable levels of reliability, requiring the replacement of all the main cables and power supplies.

Operating and maintenance costs of the innovative power system still remain high. However, despite numerous service outages, the system was a success with the public, gaining up to 190,000 passengers per day.