noun
motorcycle police; traffic police on motorcycles
Refers to the officers or the unit, not just the vehicle. Abbreviation of 白バイ隊員.
See also: 白バイ隊員
白バイが交差点で交通整理をしていた。
The motorcycle police were directing traffic at the intersection.
noun
white police motorcycle
Specifically the white-colored motorcycle used by Japanese traffic police. Often seen in the phrase 白バイに乗る.
白バイがサイレンを鳴らして走り去った。
The white police motorcycle sped away with its siren on.