In Australia, whistle posts consist of a pole or upright flat-bottom rail with a white or reflective yellow X.
Estonian whistle posts are inverted pear-shaped white plates, the lower third of which is green.
An additional white board with a black 'J' for "jour" ('day') indicates that the sign does not apply at night time.
[1][2] Whistle posts in the United States and Canada are traditionally placed 1⁄4 mile (400 m) in advance of a road crossing.
[3] A yellow diamond with black edges, Signal 67,[5] or one of its varieties, is placed 250–500 metres before halts and level crossings, where the public is not otherwise warned about approaching trains.
[6] In the People's Republic of China, a whistle board is a white diamond with a black border with the character míng 鸣 ('whistle') on it.
One modern variation found in Scotland is the 'continuous' whistle board, comprising a white rectangle with the W below a diagonal cross.