MUTCD W10-21 · Warning signs
Busway crossing ahead
What it means
Warns of busway crossing ahead.
What to do about it
It is a warning sign: the yellow diamond warns of a condition ahead so you can slow down and be ready before you reach it. (MUTCD W10-21.)
Practice this on the real test format
Signs are the part of the DMV written test people fail on, because reading them is a skill rather than a fact to memorize. Aprobify drills all 1034 of them, and tells you why each answer is what it is.
Get the appSign designations follow the MUTCD and the California MUTCD published by Caltrans; meanings are checked against the California Driver's Handbook (DL 600, rev. 6/2025). Edited by Fernando Aguilera. Aprobify is not affiliated with the California DMV.
Signs in the same family
These sit next to it in the warning signs series — the ones most easily mixed up with it.
- W10-14aP Supplemental plaque directing to use next crossing
- W10-14P Supplemental plaque indicating next crossing information
- W10-15P Supplemental plaque warning of rough railroad crossing
- W10-16 Activated blank-out sign warning of another train approaching
- W10-21aP Supplemental plaque indicating signal ahead at busway crossing
- W11-1 Bicycle crossing or bicycle activity ahead
