Warning Road Sign (W12-2)
Low Clearance Overhead Sign Meaning & Driving Rules
The Low Clearance sign warns that an overhead bridge, tunnel, or structure has the maximum vertical clearance shown on the sign.
What does the Low Clearance Overhead sign mean?
A Low Clearance sign means the overhead structure has the vertical clearance displayed on the sign. If your vehicle's total height—including rooftop cargo—meets or exceeds that clearance, do not proceed; stop safely and use another route.
Required Driver Action & Right-of-Way Protocol
Know your vehicle's exact total height. If your vehicle exceeds the posted clearance, stop and find an alternate route.
Detailed Overview & Purpose
The Low Clearance sign (W12-2) indicates the exact vertical clearance under an overhead structure. Any vehicle taller than the posted height will strike the structure, causing severe damage or bridge collapse.
Commercial trucks, RVs, delivery vans, and vehicles with rooftop cargo must know their exact height before proceeding.
Key Standard & Origin: The clearance posted on the sign is often 3 inches less than the actual measured clearance to provide a safety margin.
Where You'll Find This Sign
Posted on and in advance of low railroad bridges, tunnels, and overpasses with clearance under 14 feet.
Common Driver Mistakes to Avoid
Drivers of rental moving trucks (like U-Hauls) forgetting their vehicle height and driving into low bridges.
How This Sign Appears on the DMV Knowledge & Road Test
Essential question for CDL applicants, RV operators, and rental truck drivers.
Legal Penalties and Moving Violations
A bridge strike can lead to citations, vehicle and infrastructure damage, towing costs, and civil liability. Exact penalties depend on state law and the damage caused.
When you encounter the official Low Clearance Overhead (W12-2) on a roadway, what is your legal duty?
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