grid yet does not require the larger wire clearance for or require dual-voltage capability for trains also operating on lines. Examples are: Metro-North Railroad's New Haven Line from Pelham, NY to New Haven, CT (Since 1985; previously 11kV 25Hz). 12 kV at 25 Hz New Jersey Transit's North Jersey Coast Line from Matawan, NJ to Long Branch, NJ (1988–2002; changed to 25kV 60Hz). Amtrak SEPTA - Both ex-Reading Rail and ex-Pennsylvania Rail sides. 6.25 kV AC Early 50Hz AC railway electrification in the United Kingdom was planned to use sections at where there was limited clearance under bridges and in tunnels. Rolling stock was dual-voltage with automatic switching between and . The sections were converted to as a result of research work that demonstrated that the distance between live and earthed equipment could be reduced from that originally thought to be necessary. The research was done using a steam engine beneath a bridge at Crewe. A section of overhead line was gradually brought closer to the earthed metalwork of the bridge whilst being subjected to steam from the locomotive's chimney. The distance at which a flashover occurred was measured and this was used as a basis from which new clearances between overhead equipment and structures were derived. 50 kV AC Occasionally is doubled to to obtain greater power and increase the distance between substations. Such lines are usually isolated from other lines to avoid complications from interrunning. Examples are: The Sishen–Saldanha iron ore railway (). The Deseret Power Railway which was an isolated coal railway (). The now closed Black Mesa and Lake Powell Railroad which was also an isolated coal railway (). The now closed Tumbler Ridge Subdivision of BC Rail (). 2 × 25 kV autotransformer system The 2 × 25kV autotransformer system is a split-phase electric power system which supplies 25kV power to the trains, but transmits power at 50kV to reduce energy losses. It should not be confused with the 50kV system. In this system, the current is mainly carried between the overhead line and a feeder transmission line instead of the rail. The overhead line (3) and feeder (5) are on opposite phases so the voltage between them is 50kV, while the voltage between the overhead line (3) and the running rails (4) remains at 25kV. Periodic autotransformers (9) divert the return current from the neutral rail, step it up, and send it along the