A permanent marker placed at a specific distance ahead of a public grade crossing, usually a quarter mile. It tells the locomotive engineer exactly when to start the standard crossing warning sequence of two longs, a short, and a long blast. The sign typically features a large letter W painted on a white background.
Heard on the job
I started blowing right at the whistle post, but that truck still tried to beat us across the diamond.
Insider tip
Even though steam engines are long gone, the sign still says W for whistle, not H for horn.
Also heard as
- W board