Editing Third rail (section)

=== Safety ===
[[File:Embossed third rail side contact ramp.jpg|thumb|Entry ramp for side-contact third rail.]]
Because third-rail systems, which are located close to the ground, present [[electric shock]] hazards, high voltages (above 1500&nbsp;V) are not considered safe. A very high current must therefore be used to transfer adequate power to the train, resulting in high [[resistive loss]]es, and requiring relatively closely spaced feed points ([[electrical substation]]s).

The electrified rail threatens [[electrocution]] of anyone wandering or falling onto the tracks. The risk of falling can be avoided by using [[platform screen doors]], or the risk can be reduced by placing the conductor rail on the side of the track away from the platform, when allowed by the station layout, or by covering the conductor rail with a '''coverboard''', a plank supported by [[Bracket (architecture)#Specialized brackets|brackets]]. However, coverboards often cannot be used because they reduce the [[structure gauge]] near the top of rail and thereby also the [[loading gauge]].

There is also a risk of pedestrians walking onto the tracks at [[level crossings]] and accidentally touching the third rail, unless [[grade separation]] is fully implemented. In the United States, a 1992 [[Supreme Court of Illinois]] decision affirmed a $1.5 million verdict against the [[Chicago Transit Authority]] for failing to stop an intoxicated person from walking onto the tracks at a level crossing at the [[Kedzie station (CTA Brown Line)|Kedzie station]] in an apparent attempt to urinate.<ref>''Lee v. Chicago Transit Authority,'' 152 Ill.2d 432, 605 N.E.2d 493 (1992).</ref>

The end ramps of conductor rails (where they are interrupted, or change sides) present a practical limitation on speed due to the mechanical impact of the shoe, and {{convert|161|km/h|0|abbr=on}} is considered the upper limit of practical third-rail operation. The world speed record for a third rail train is {{cvt|109|mph|order=flip}} attained on 11 April 1988 by a British [[British Rail Class 442|Class 442]] [[Electric multiple unit|EMU]].<ref name=":0">{{cite web|title=Class 442 Feature – The Early Years|url=http://extra.southernelectric.org.uk/features/rolling-stock/442/442nse02.html|access-date=2021-06-23|website=extra.southernelectric.org.uk}}</ref>

In the event of a collision with a foreign object, the beveled end ramps of bottom running systems can facilitate the hazard of having the third rail penetrate the interior of a passenger car. This is believed to have contributed to the death of five passengers in the [[Valhalla train crash]] of 2015.<ref>{{cite news | url=https://www.nytimes.com/interactive/2015/02/04/nyregion/2015-02-04-metro-north-crash.html | title=Investigating the Metro-North Crash | work=The New York Times | date=4 February 2015 | access-date=15 February 2015}}</ref>

Modern systems, such as [[ground-level power supply]] (first used in the [[tramway of Bordeaux]] in 2003), avoid the safety problem by segmenting the powered rail, with each segment being powered only when fully covered by the vehicle which utilizes its power.<ref name="groundlevelpowersupply" />