level in 1.5 cm wide channels, and one (or several) earthed at surface level. 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". Modern implementations Ansaldo Stream The first modern ground-level power supply system to be developed is the Ansaldo Stream system. STREAM is an acronym that stands for "Sistema di TRasporto Elettrico ad Attrazione Magnetica", meaning "System of Electric Transport by Magnetic Attraction". The system uses a channel in the road made of insulating composite fiberglass material which contains a flexible copper strip; a vehicle passing over the channel with a special magnetic contact shoe raises the conductor to the surface, allowing power to flow to the vehicle. Segments of the strip are powered only when a vehicle passes over them. The system was developed in 1994 and trialed on a public tram line in 1998, which was eventually dismantled in 2012. Alstom APS Alstom APS uses a third rail placed between the running rails, divided electrically into 11-metre segments. These segments automatically switch on or off by radio control according to whether a tram is passing over them, thereby eradicating any risk to other road users. The tram has two collector shoes, and two segments of rail are active at any given time, to avoid interruption of power when passing between segments. 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, becoming the first modern commercial ground-level power supply system. From 2011, the technology has been used in a number of other cities around the world. Alstom further developed the system for use with buses and other vehicles, which it dubs Alstom SRS. Alstom SRS has been tested for compatibility with snow plows and for safety under exposure to snow, ice, salting, and saturated brine. CAF ACR Construcciones y Auxiliar de Ferrocarriles (CAF) trialed its Acumulador de Carga Rápida (ACR) ground-level power supply system in 2007 in Seville. Sections of the Seville MetroCentro tramway around the Seville Cathedral were converted to the ACR ground-level power supply system. ACR’s first commercial installation was aboard Urbos trams supplied to MetroCentro in