MUTCD R4-1 · Regulatory signs
Prohibits passing other vehicles
What it means
Prohibits passing other vehicles.
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 R4-1.)
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.
- R3-33aL Vertical version of the left lane must exit sign
- R3-33aR Vertical version of the right lane must exit sign
- R3-33L Traffic in the left lane must leave the freeway at the upcoming exit
- R3-33R Traffic in the right lane must leave at the upcoming exit
- R4-2 Allows passing but requires caution
- R4-3 Directs slower moving traffic to stay in the right lane
