|Supplementary Plates below signs|
|An example of a bend sign with a supplementary plate|
Some signs require supplementary plates explaining where the hazard is, how far it is to the hazard, or for how far it extends. These generally consist of a white plate, with black borders and text, mounted beneath the sign to which they refer.
Since the Traffic Signs Manual considers a sign and its plate tobe one sign, you can see more than three signs on one pole; however, this is discouraged. Some signs may incorporate a supplementary plate if the sign has a yellow, or grey border; this is beneficial as it reduces the risk of the plate becoming misaligned. Over-use of borders, however, can lead to a loss of the impact that a border is intended to provide.
Special plates associated with particular signs are dealt with be on those signs' pages.