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The installation of overhead lines may require reconstruction of bridges to provide safe electrical clearance. [20] Overhead lines, like most electrified systems, require a greater capital expenditure when building the system than an equivalent non-electric system. While a unelectrified railway line requires only the grade, ballast, ties and ...
A related but separate gauge is the loading gauge: a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. The difference between these two gauges is called the clearance .
Overhead lines or overhead wires are used to transmit electrical energy to trams, trolleybuses or trains. Overhead line is designed on the principle of one or more overhead wires situated over rail tracks. Feeder stations at regular intervals along the overhead line supply power from the high-voltage grid.
The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with superelevation (difference in elevation of the two rails) in the case of train tracks , determines the ...
The red Euler spiral is an example of an easement curve between a blue straight line and a circular arc, shown in green. This sign aside a railroad (between Ghent and Bruges) indicates the start of the transition curve.
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 50 kV, while the voltage between the overhead line (3) and the running rails (4) remains at 25 kV. Periodic autotransformers (9 ...
The overhead wiring, generally having two separate overhead lines and the rail for the third phase, was more complicated, and the low frequency used required a separate generation or conversion and distribution system. Train speed was restricted to one to four speeds, with two or four speeds obtained by pole-changing or cascade operation or both.
Until 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. [15] After 2010 third rails were used in spite of level crossings. The third rails have gaps, but there are two contact ...