Low clearance sign: what it means

Low clearance sign: a yellow diamond with a black arrow pointing up, the height 12 feet 6 inches, and a black arrow pointing down
Drawing: Drivoku, based on MUTCD sign W12-2. Simplified; real signs follow the FHWA Standard Highway Signs specifications.

The low clearance sign shows the height of a bridge or other structure over the road ahead. Taller vehicles must not go under it.

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What does the low clearance sign mean?

MUTCD Section 2C.25 says the Low Clearance (W12-2) sign shall be used to warn of vertical clearances less than 14 feet 6 inches, or less than 12 inches above the legal maximum vehicle height. The clearance shown should not be more than the actual clearance.

Quick quiz

What does the sign at the top of this page mean?

  1. No vehicles over the weight shown.
  2. The bridge ahead is narrower than the road.
  3. Low overhead clearance ahead.

Show answer

C. Low overhead clearance ahead. It warns of a low vertical clearance ahead (MUTCD Section 2C.25). Source: MUTCD 11th Edition, Chapter 2C, Warning Signs and Object Markers: Section 2C.25, FHWA; MUTCD 11th Edition, FHWA

Where will you see it?

Before low bridges, underpasses and tunnels, and at the last place to turn around.

What should you do?

Know the height of your vehicle and load. If you are too tall, turn off before the structure.

What do people get wrong?

Forgetting a roof box, a trailer or a rental truck’s extra height.

Common questions

Does it matter for cars?

Rarely, but it does with a tall load, a roof box or a rental moving truck.

Is there a sign on the bridge itself?

Section 2C.25 says a Low Clearance Overhead sign may be installed on the structure too.

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Sources

Checked on 4 November 2026 against the MUTCD 11th Edition (FHWA), Section 2C.25.

  1. MUTCD 11th Edition, Chapter 2C, Warning Signs and Object Markers: Section 2C.25, FHWA
  2. MUTCD 11th Edition, FHWA. FHWA lists the current version as the 11th Edition with Revision 1, dated December 2025

Sign pictures are our own simplified drawings of the MUTCD designs, which are in the public domain (MUTCD Section 1D.06). Sources and image credits.

This text was written with AI help, checked against the MUTCD and approved by Fri Vei AS. Last updated .

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