Low Clearance Signs

You measure the true clearance at its lowest point and round down to the nearest inch - never up - so the sign never promises more room than exists. In areas with winter frost heave, the posted number is reduced by up to 3 inches because the pavement rises toward the beam. For an exact figure, order a custom "Clearance __ Ft __ In" sign set to your measurement.

Yes. The clearance is measured vertically from the road surface up to the lowest point of the structure overhead - a sagging beam, a pipe, the underside of the deck, whatever hangs down farthest. That lowest point governs, because it's what a tall vehicle hits first. The measured figure is then rounded down to the nearest inch before it goes on the sign, so the posted number is always a safe minimum.

If a posted height looks incorrect, faded, or missing on a public road, report it to the agency that owns the road - your city or county public works department, or the state DOT for a state route or highway. Give the exact location and structure. They are responsible for verifying the clearance and correcting the sign. If it is private property, garage, or car wash, the owner handles it, and we can supply the replacement.

Put a low clearance sign directly on the structure so the height shows at the hazard. Post an advance sign with a distance plaque at the nearest intersecting road or wide spot where an over-height vehicle can turn around. The advance sign is important because it gives a tall truck a way out before it is trapped under the bridge with nowhere to go.

The advance sign is the yellow diamond W12-2, posted up the road to warn drivers while they can still detour. The sign on the structure is the rectangular W12-2a, mounted on the bridge or beam with the same clearance legend, as a last-second confirmation right at the point of the hazard. Most low structures get both.

Both. We stock round heights - 7 ft, 8 ft, 9 ft, 10 ft, and 12 ft - ready to ship. For any other measurement, the custom clearance sign lets you set the exact feet and inches.

For a garage, covered entrance, or car wash bay, use the Low Clearance symbol sign with the height at the entry, before the driver commits to the ramp or tunnel. The symbol version - two arrows pointing inward to a height, the same idea used on international clearance signs - reads at a glance regardless of language, which suits public garages. To physically stop over-height vehicles before they reach the concrete, add Height Guard clearance bars - a swinging bar set to the limit gives a harmless warning tap.

Yes. If no tall vehicle should be on the road at all, a No Trucks - Low Clearance - Cars Only sign steers them away before they reach the structure. For a bulk order or a custom message, call our sales team at 888-343-3771 (Mon-Fri, 8am-7pm EST) or email customerservice@smartsign.com.