Turnouts are mechanisms used for converting rails during train operation and the mechanism consists of two parts, the switch rail & stock rail and the crossing & wing rail. When the switch rail and crossing lean to the left, the train will operate along the right track; on the contrary, when the switch rail and crossing lean to the right, the train will operate along the left track. The switch in the HSR system consists of a motor, a connection rod and a snap switch. The motor induces the connection rod to push or pull the switch rail & crossing which will lead to change of the operating route. To avoid derailment during route change, the operation speed has to be limited. When the turnout angle is larger, the turnout is shorter and will allow lower speed limit; on the other hand, when the turnout angle is smaller, the turnout is longer and will allow higher speed limit.
Owing to HSR operating demands including first, 90-min operation time from Taipei to Zuoying for express trains; second, 120-min operation time from Taipei to Zuoying for commuter trains; and third, requirement of under 130-160 km/h during rail change for commuter trains, the HSR system requires longer switch rails and crossings comparing to other rail systems. With longer switch rails, multiple switches are needed to simultaneously push/pull the switch rail & crossing and achieve a smooth contact surface. With tight adherence of the switch rail and crossing to the stock rail, stability and safety of HSR rail conversion can be assured.