What is a Frog?

What is a Frog?

• A. A device at grade crossings that marks speed.
• B. A track structure used at the intersection of two running rails to provide support for wheels and passageways for flanges, thus permitting wheels on either rail to cross the other.
• C. A safety barrier near stations.
• D. A signaling relay station.

Answer: (B)

A frog is the track piece at the intersection of two running rails that lets wheels cross from one rail to the other. It provides a crossing path for wheel flanges and supports the wheel as it moves across the crossing, which is essential for switches and crossovers to function smoothly. The wheel flange guides the wheel onto the opposite rail while keeping the overall track gauge intact, so trains can pass from one route to another without derailment. Other options describe different devices: one marks speed at grade crossings, another is a safety barrier near stations, and another is part of signaling equipment. Those serve separate purposes and don’t provide the crossing path for wheels between rails.

A frog is the track piece at the intersection of two running rails that lets wheels cross from one rail to the other. It provides a crossing path for wheel flanges and supports the wheel as it moves across the crossing, which is essential for switches and crossovers to function smoothly. The wheel flange guides the wheel onto the opposite rail while keeping the overall track gauge intact, so trains can pass from one route to another without derailment. Other options describe different devices: one marks speed at grade crossings, another is a safety barrier near stations, and another is part of signaling equipment. Those serve separate purposes and don’t provide the crossing path for wheels between rails.