page_title: Pantograph (transport)
section_title: Metro systems and overhead lines
hierarchical_section_title: Pantograph (transport) / Metro systems and overhead lines
context_page_description: A pantograph is an apparatus mounted on the roof of an electric train, tram, trolleybus, trolley truck or electric bus to collect power through contact with an overhead line. Battery electric buses and trains are charged at charging stations. It is a common type of current collector. Typically, a single or double wire is used, with the return current running through the rails. The term stems from the resemblance of some styles to the mechanical pantographs used for copying handwriting and drawings.
context_section_description: Most rapid transit systems are powered by a third rail, but some use pantographs, particularly ones that involve extensive above-ground running. Most hybrid metro-tram or 'pre-metro' lines whose routes include tracks on city streets or in other publicly accessible areas, such as line 51 of the Amsterdam Metro, the MBTA Green Line, RTA Rapid Transit in Cleveland, Frankfurt am Main U-Bahn, and San Francisco's Muni Metro, use overhead wire, as a standard third rail would obstruct street traffic and present too great a risk of electrocution.
  Among the various exceptions are several tram systems, such as the ones in Bordeaux, Angers, Reims and Dubai that use a proprietary underground system developed by Alstom, called APS, which only applies power to segments of track that are completely covered by the tram. This system was originally designed to be used in the historic centre of Bordeaux because an overhead wire system would cause a visual intrusion. Similar systems that avoid overhead lines have been developed by Bombardier, AnsaldoBreda, CAF, and others. These may consist of physical ground-level infrastructure, or use energy stored in battery packs to travel over short distances without overhead wiring.
  Overhead pantographs are sometimes used as alternatives to third rails because third rails can ice over in certain winter weather conditions. The MBTA Blue Line uses pantograph power for the entire section of its route that runs on the surface, while switching to third rail power before entering the underground portion of its route. The entire metro systems of Sydney, Madrid, Barcelona, Shanghai, Hong Kong, Seoul, Kobe, Fukuoka, Sendai,  Jaipur, Chennai, Mumbai and Delhi use overhead wiring and pantographs (as well as certain lines of the metro systems in Beijing, Chongqing, Noida, Hyderabad, Tokyo, Osaka, Nagoya, Singapore and Sapporo). Pantographs were also used on the Nord-Sud Company rapid transit lines in Paris until the other operating company of the time, Compagnie du chemin de fer métropolitain de Paris, bought out the company and replaced all overhead wiring with the standard third rail system used on other lines.
  Numerous railway lines use both third rail and overhead power collection along different portions of their routes, generally for historical reasons. They include the North London line and West London lines of London Overground, the Northern City Line of Great Northern, four of the five lines in the Rotterdam Metro network, Metro-North Railroad's New Haven Line, and the Chicago Transit Authority's Yellow Line. In this last case, the overhead portion was a remnant of the Chicago North Shore and Milwaukee Railroad's high-speed Skokie Valley Route, and was the only line on the entire Chicago subway system to utilize pantograph collection for any length.  As such, the line required railcars that featured pantographs as well as third rail shoes, and since the overhead was a very small portion of the system, only a few cars would be so equipped.  The changeover occurred at the grade crossing at East Prairie, the former site of the Crawford-East Prairie station.  Here, trains bound for Dempster-Skokie would raise their pantographs, while those bound for Howard would lower theirs, doing so at speed in both instances.  In 2005, due to the cost and unique maintenance needs for what only represented a very small portion of the system, the overhead system was removed and replaced with the same third rail power that was used throughout the rest of the system, which allowed all of Chicago's railcars to operate on the line. All the pantographs were removed from the Skokie equipped cars.
  In 2010, the Oslo Metro line 1 changed from third rail to overhead line power at Frøen station. Due to the many level crossings, it was deemed difficult to install a third rail on the rest of the older line's single track. After 2010 third rails were used in spite of level crossings. The third rails have gaps, but there are two contact shoes.
caption: Symmetrical, diamond-shaped pantographs on a Prague tram
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