Wye (rail)

A wye, in railway terminology, is a triangular junction of tracks used to reverse the direction of railway vehicles, or to connect a branch line or siding with the main line. It consists of three switches (points) arranged in a triangular shape. One side of the triangle typically connects to the main track, while the other two sides form the legs of the wye.

The operation of a wye involves entering the wye from one leg, proceeding onto the track of the triangle's apex opposite that leg, then reversing direction and exiting through the other leg. This results in the railway vehicle being turned 180 degrees.

Wyes are particularly useful in situations where turning loops are impractical or unavailable, such as in constrained spaces or at the end of a branch line where continuous loop operation is not required. They can also be used to turn entire trains, although this requires the wye to be of sufficient length.

While wyes are functionally similar to turntables, they take up more space but generally require less maintenance. They are a common feature in railway yards and at the end of some passenger or freight lines.

The term "wye" is derived from the shape of the track layout, which resembles the letter "Y".