Wig-wag (automobile)

In its traditional form a wig-wag emits the right and left headlamps alternately, with each lamp lit for around half a second at a time.

When highbeam headlights are flashed, the wig-wag may create glare or temporarily blind the drivers of oncoming 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.

In the United States, motorcycles are similarly allowed to be equipped with a white (clear) lights (LED) headlamp modulator to increase conspicuity during the daytime.