Low Clearance Sign
The low clearance sign shows the maximum vehicle height that can safely pass under a bridge, overpass, or tunnel. Vehicles taller than the posted measurement must not proceed.
Last updated: April 4, 2026
Low clearance signs are posted where the vertical clearance under a structure is restricted. The measurement shown is the maximum height of any vehicle, including roof racks, antennae, and loads, that can safely pass. In Ontario, standard road clearance is 5.0 metres, but older structures, railway underpasses, and urban tunnels may be significantly lower.
Quick Facts
Type
Warning Sign
Shape
Diamond or rectangular
Colours
Yellow background with black bridge or tunnel symbol and height measurement
In this guide
What does the Low Clearance Sign mean?
Low clearance signs are posted where the vertical clearance under a structure is restricted. The measurement shown is the maximum height of any vehicle, including roof racks, antennae, and loads, that can safely pass. In Ontario, standard road clearance is 5.0 metres, but older structures, railway underpasses, and urban tunnels may be significantly lower.
What to do when you see it
Know the height of your vehicle, especially when towing or carrying loads on a roof rack. If your vehicle exceeds the posted clearance, do not attempt to pass. Find an alternate route. If you realize too late and have stopped under or near the structure, reverse carefully if safe, or call for assistance.
Where you'll see it in Ontario
Low clearance signs are found at railway underpasses, older bridges in urban areas, parking garage entrances, and on some rural roads. In Toronto and Vaughan, certain railway underpasses have very low clearances that affect campers and large vans.
G1 test relevance
Low clearance is primarily a concern for commercial vehicle drivers, but G1 questions may ask about this sign in the context of identifying warning signs and understanding the need to know your vehicle dimensions.
Common mistakes drivers make
Trying to squeeze through a clearance that is slightly less than the vehicle height is dangerous and can result in structural damage to both the vehicle and the bridge. It also blocks the road for all traffic behind.
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