A locomotive blue light reverser key has a handle portion and a shaft portion that is connected to the handle portion. The handle portion includes a Light Emitting Diode (LED), a switch, a battery that powers the LED, and a blue tinted lens. The shaft portion is insertable into a reverser of a locomotive. During a blue signal procedure when the train is not permitted to move, a train operator uses the blue light reverser key to indicate the blue signal procedure is in effect. The train operator activates the LED on the handle portion and inserts the blue light reverser key into the reverser. The shaft portion does not engage any locking mechanism within the reverser, and the reverser key prevents the locomotive from moving forward or backward. The blue light emitted from the blue light reverser key also notifies other train operators of the blue signal procedure.