Low Clearance 12'6" Sign
Overhead clearance ahead is only 12 feet 6 inches
In short: A 12′-6″ clearance sign warns that the maximum available height under the bridge or structure is 12 feet 6 inches. Drivers of trucks, RVs, trailers, and roof-loaded vehicles must know their total height and take another route if it may not fit.
What to do
Check vehicle height. Find alternate route if too tall.
Tips
Common at bridges and underpasses.
Test yourself
You see this sign while driving. What do you have to do?
Show the answer
Check vehicle height. Find alternate route if too tall.
Common mistake
Not knowing vehicle height
How to recognize this sign
Searchers also call this a 12-6 sign, bridge-height sign, overhead-clearance sign, or low-clearance warning.
Do not confuse it: The posted number is vertical clearance, not a speed, distance, weight, or vehicle-length limit.
About warning signs
Warning signs are diamond-shaped and yellow with black symbols. They alert you to hazards ahead — curves, intersections, crossings — so you have time to slow down. On the DMV written test, expect several questions asking what a specific warning sign means and what action it calls for.
Practice questions about this sign
This sign above an underpass tells you:
- A. The greatest height a vehicle can be to pass under it
- B. How far it is to the next underpass
- C. The lowest speed allowed under the structure
- D. The weight limit for the bridge overhead
Show answer
A. The greatest height a vehicle can be to pass under it — A low clearance sign posts the vertical space under the structure. Measure your vehicle with its load, and if you are taller than the posted figure, take another route rather than risk striking the overpass.
Universal rule · checked against MUTCD 11th Edition, Part 2, Chapter 2C — Warning Signs — Traffic Signs — Warning Signs · verified 2026-08-22
Frequently asked questions
What does the Low Clearance 12'6" Sign mean?
Overhead clearance ahead is only 12 feet 6 inches
What should you do at a Low Clearance 12'6" Sign?
Check vehicle height. Find alternate route if too tall.
Reference standard: Federal Highway Administration Manual on Uniform Traffic Control Devices ↗. State and local agencies may add rules or operating times, so follow the complete posted sign where you drive. How DMV Prep sources content.
Studying for a car permit instead? Drill all 111 signs with flashcards.
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