Wig-wag (automobile)

NWAS ambulance displays the operation of a wig-wag: only one headlight operates at a time, with the two flashing alternately at a preset rate.

A wig-wag is a device for flashing an automobile's headlamps at a preset rate. In its traditional form a wig-wag constitutes the illuminating of the right and left headlamps alternately, with each lamp lit for around half a second at a time. In the United Kingdom the wig-wag is only seen on the road on emergency vehicles. The 'standard' wig-wag is often used within a cycle of other illumination patterns, such as swiftly alternating the left and right headlights, alternating the left and right headlights slowly, or flashing both headlights together, and using a mixture of high- and low-/dipped-beams.

Although the use of flashing headlights does increase the visibility of any vehicle, it can also create problems. In situations when highbeam headlights are flashed, the wig-wag may create glare or may otherwise temporarily blind the drivers of oncoming vehicles.

Generally, wig-wags are prohibited on all vehicles except emergency vehicles.^[1] However the road rules in New South Wales, Australia, and some areas in the United States allow school buses to have flashing headlights. ^[2] In New South Wales specifically additional Wig-Wag lights (separate from the headlights) are used on all public transport buses.

Notes

See also

• Emergency vehicle equipment