ELECTRO-DIESEL TRAM-TRAINS AND THEIR PROSPECTS

摘要

In 1992, the German city of Karlsruhe introduced a new urban rail service - with a new type of vehicle - that enabled passengers to travel from suburban areas into the centre of the city without having to transfer from the railway to the tramway. This time- and energy-saving proposition was not new, but christened 'tram-train' for the modern era it was an immediate success. The concept soon caught on and tram-trains now serve many European city regions, providing the same convenience to passengers by allowing higher-speed running on segregated rail routes, but the convenience of connections into more densely-populated urban hubs. If the railway connecting the suburbs with the city is electrified, passengers can be delivered to the central districts by a dual-voltage tram-train, operating like an electrified train on regional rail routes and like an urban tram when traversing city streets. On the railway, electric tram-trains operate under 25kV 50Hz; 15kV 16.7Hz or 1.5kV dc overhead power lines; in urban environments the standard is generally 600 or 750V dc. However, if the alignment that stretches beyond the city limits cannot or will not be electrified (there are many reasons for such decisions), it has been possible to provide the required tractive effort through the use of onboard diesel power - hence the introduction of the electro-diesel tram-train. This 'bi-mode' form operates likes a Diesel Multiple Unit (DMU) on the railway, turning off the diesel-generator powerplant and transferring to direct current overhead supply via pantograph for tramway sections.