Wigwag

Wigwag is a nickname for a type of railroad grade crossing signal once common in North America, referring to its pendulum-like motion that signaled a train's approach. The device is generally credited to Albert Hunt, a mechanical engineer at Southern California's Pacific Electric (PE) interurban streetcar railroad, who invented it in 1909 for safer railroad grade crossings. The term should not be confused with its usage in Britain, where "wigwag" generally refers to alternate flashing lights, such as those found at modern level crossings.