do turn signal lights have to be yellow
Automotive lighting The colour of light emitted by vehicle lights is largely standardised by longstanding convention. It was first codified in the 1949 Vienna Convention on Road Traffic and later specified in the 1968 United Nations Convention on Road Traffic.[5][6] With some regional exceptions, lamps facing rearward must emit red light, lamps facing sideward and all turn signals must emit amber light, while lamps facing frontward must emit white or selective yellow light. No other colours are permitted except on emergency vehicles.
School bus yellow School bus yellow is a color which was especially formulated for use on school buses in North America in 1939. The color is now officially known in Canada and the U.S. as National School Bus Glossy Yellow and was originally called National School Bus Chrome. The pigment used for this color was, for a long time, the lead-containing chrome yellow.[1]