MUTCD R10-31P · Regulatory signs
Supplemental plaque indicating rule applies at signal location
What it means
Supplemental plaque indicating rule applies at signal location.
What to do about it
It is a regulatory sign: it states a law you must obey, not a suggestion. Ignoring it is a citable violation. (MUTCD R10-31P.)
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 regulatory signs series — the ones most easily mixed up with it.
- R10-27 Allows left turn after stop and yield on flashing red arrow
- R10-28 Limits to one vehicle per green signal phase
- R10-29 Limits to one vehicle per green signal phase in each lane
- R10-30 Requires right turn on red to yield to U-turning vehicles
- R10-32P Instructions to push button for 2 seconds to get extra crossing time
- R10-40 Mandatory turn movement for bicycle signal
