Young Curly Blonde Girl Changes The Railroad Switch On The Railway Track

A derailer works by derailing any vehicle passing over it. There are different types of derailer, but in some cases they consist of a single switch point installed in a track. The point can be pulled into a position to derail any equipment that is not supposed to pass.
• Dual gauge switches
Dual gauge switches are used in dual gauge systems. There are various possible scenarios involving the routes that trains on each gauge may take, including the two gauges separating or one gauge being able to choose between diverging paths and the other not. Because of the extra track involved, dual gauge switches have more points and frogs than their single gauge counterparts. This limits speeds even more than usual.
A related formation is the 'swish' or rail exchange, where (usually) the common rail changes sides. These have no moving parts, the narrower gauge wheels being guided by guard rails as they transition from one rail to another. The wider gauge only encounters continuous rail so is unaffected by the exchange. At dual gauge turntables, a similar arrangement is used to move the narrow gauge track from one side to a central position.