Alstom APS, also known as Alimentation par Sol or Alimentation Par le Sol (which literally means "feeding via the ground"), is a form of ground-level power supply for street trams and, potentially, other vehicles. APS was developed by Innorail, a subsidiary of Spie Enertrans but was sold to Alstom when Spie was acquired by Amec. It was originally created for the Bordeaux tramway, which was constructed from 2000 and opened in 2003. From 2011, the technology has been used in a number of other cities around the world.
APS is used, primarily for aesthetic reasons, as an alternative to overhead lines. As such it competes with other ground-level power supply systems, but also with energy storage systems such as batteries. In 2015, Alstom developed a derivative of APS, Alstom SRS (Système de Recharge statique par le sol or static-based ground charging system), which can be used to recharge battery powered trams and buses whilst they are stationary at stops.
APS uses a third rail placed between the running rails, divided electrically into 11-metre segments. These segments automatically switch on and off according to whether a tram is passing over them, thereby eradicating any risk to other road users.Each tram has two power collection shoes, next to which are antennas that send radio signals to energise the power rail segments as the tram passes over them. At any one time, two consecutive segments under the tram will be live.
APS is different from the conduit current collection system (which was one of the first ways of supplying power to a tram system) as the latter involves burying a third and fourth rail in an underground conduit (‘vault’) between the running rails. Conduit current collection was used in historic tram systems in Washington, Manhattan, Paris, Berlin, Marseilles, Vienna, Budapest and London. It fell into disuse because overhead wires proved much less expensive and troublesome for street railways.
Use in BordeauxEdit
Modern ground-level current collection was pioneered by the Bordeaux tramway in France. The public had assumed that the new system would use a traditional conduit system, like that of the Bordeaux trams which ran prior to 1958 and objected when they learned that it was not considered safe and that overhead wires were to be used instead. Facing complaints both from the public and the French Ministry of Culture, planners developed APS as a modern way of replicating the conduit system.
Before use in Bordeaux, APS was tested and proved viable on a short section of reserved-track in the French city of Marseille. Nevertheless, Bordeaux has experienced problems, with APS being so temperamental that, at one stage, the Mayor issued an ultimatum that if reliability could not be guaranteed, it would have to be replaced with overhead wires.
Problems have included water-logging, when the water does not drain quickly enough after heavy rain.
In other citiesEdit
In addition to the lead city of Bordeaux, APS has also been implemented on a number of other tram systems in France and around the world:
|Dubai Tram||Dubai||United Arab Emirates||2014||The system is fully equipped with APS over its entire passenger route length, and thus trams do not use their pantographs unless travelling within the depot area.|
|VLT Carioca||Rio de Janeiro||Brazil||2016||The system mainly uses APS, however where this was deemed impractical, the trams employ Alstom's proprietary supercapacitor-based energy storage system.|
|CBD and South East Light Rail||Sydney||Australia||2019||The system uses APS within the Sydney CBD and conventional overhead wires elsewhere|
|Cuenca tram||Cuenca||Ecuador||2020||The system uses APS in certain regions only and conventional overhead wires elsewhere.|
|Lusail LRT||Lusail||Qatar||Under construction|||
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