What is the main feature of a "wye" track layout?

A "wye" track layout is characterized by its design, which resembles the letter "Y" and is specifically intended to allow trains to turn around and head in the opposite direction. This feature is particularly useful in locations where there is a need for a train to change direction without the necessity of reversing all the way back along the same track. By providing a triangular arrangement of tracks, the wye facilitates a smooth transition for the train in a space-efficient manner.

The other options, while related to rail operations, do not accurately describe the primary function of a wye track layout. For instance, connecting multiple tracks for crossovers is typically the function of a switch or crossover point, rather than a wye. Storing idle trains is a function of storage yards or sidetracks, which are separate from the purpose of a wye layout. Additionally, while tracks may enable higher speeds in certain configurations, the main purpose of a wye is about the reversal of direction rather than speed enhancement. Therefore, the defining attribute of a wye track is its capability to turn trains around efficiently.