In rail transport use, guard rails or check rails are placed parallel to regular running rail along areas of restricted clearance, such as a bridge, trestle, or tunnel. These have the effect of keeping the wheels of rolling stock in alignment in case of derailment. It also helps to minimize damage to the structure and allow easier post-accident cleanup.
Video Guard rails (rail)
History
Although there has always been some form of guard rails as long as there have been trains, the precursor of the guard rails we have today were detailed in a patent filed by Gorham B. Ames in 1893, based in Laconia, New Hampshire in the US.
Guard-rail US 522038 A
Maps Guard rails (rail)
Sharp curves
On sharp curves, guard rails may be placed inside the inner rail, where they engage the back of the flange of the wheel on that side.
References
Source of article : Wikipedia