Ground-level power supply
Ground-level power supply, also known as surface current collection or, in French, alimentation par le sol ("feeding via the ground"), is a concept and group of technologies that enable electric vehicles to collect electric power at ground level instead of the more common overhead lines.
Systems in the 21st century, such as Alstom APS, Ansaldo Tramwave, CAF ACR, and Elways, were developed to modern standards of safety and reliability, and added the ability to supply power to electric buses, trucks, and cars.
Overhead lines were met with public opposition for aesthetic reasons, so the contractor Siemens-Halske implemented a concrete conduit underneath one of the trolley rails, with a narrow opening that allowed a "plow" to be inserted and make electrical contact with wires held by insulators at either side of the conduit.
The system fell out of favor within a few years due to the cost of excavating the conduit, and was generally replaced with overhead lines.
Underneath there was a switch mechanism that made an electrical connection with the top of the stud when a car with a strong electromagnet at its underside passed over it.
[10] Advancements in technology in the late 2010s led to ground-level power supplies seeing increasing reliability and economic feasibility.
[15] The co-director for one of the French Ministry of Ecology working groups on electric road systems stated that rail-based ERS are the most advantageous, though the specific rail technology has yet to be standardized.
[17] The second, with technology developed by Elonroad, is scheduled to undergo laboratory testing for skid effects on motorcycles before being deployed along two kilometers on the A10 autoroute south of Paris.
[13] Alstom, Elonroad, and other companies have, in 2020, begun drafting a standard for ground-level power supply electric roads.
[20] Shortly afterward, a working group of the French Ministry of Ecology recommended adopting a European electric road standard formulated with Sweden, Germany, Italy, the Netherlands, Spain, Poland, and others.
[22] The standard, CENELEC Technical Standard 50717, specifies the following: an ERS voltage of 750 volts; a contact shoe capable of withstanding impact of gravel and similar road debris at the maximum operating speed; a weak link that breaks off the current collector at the structural fixing points if the force is larger than the maximum specified by the vehicle manufacturer; automatic monitoring of the presence of ERS infrastructure; automatic engagement and disengagement; a presence signal that may be analog or digital, and optional standard bidirectional communication; ease of inspection and replacement for the wearing parts of the sliding contact; and standard tests, markings, maintenance, and operational environment conditions.
[23] Following standards, encompassing "full interoperability" and a "unified and interoperable solution" for ground-level power supply, are scheduled to be published by the end 2024, detailing complete "specifications for communication and power supply through conductive rails embedded in the road"[24][25] as specified in the proposed technical standard prTS 50740 in accordance with European Union directive 2023/1804.
STREAM is an acronym that stands for "Sistema di TRasporto Elettrico ad Attrazione Magnetica", meaning "System of Electric Transport by Magnetic Attraction".
It was originally created for the Bordeaux tramway, which started construction in 2000 and opened in 2003, becoming the first modern commercial ground-level power supply system.
[30][31] The French government reports no electrocutions or electrification accidents on any tramway in France from as early as 2003[32] until as recently as December 31, 2022.
ACR's first commercial installation was aboard Urbos trams supplied to MetroCentro in 2011, allowing the permanent removal of overhead lines around the cathedral.
