Where:
On any road where there is a structure or obstacle overhead, such as a bridge, tunnel, overhead cable, sign gantry, or subway, that limits the maximum height of vehicles that can pass safely underneath.
These are commonly found on roads leading under bridges or through tunnels.

Purpose:
To warn that there is a height restriction ahead, meaning vehicles exceeding a certain height cannot safely pass beneath the structure.
The sign helps prevent collisions with overhead structures, which can cause severe damage to vehicles, infrastructure, and endanger other road users.

Action:
Be alert for accompanying height restriction signs, which will indicate the exact clearance height in metres.
If you are driving a tall vehicle (such as a truck, bus, caravan, or vehicle carrying a high load), ensure that your vehicle’s height is within the allowed limit.
If it exceeds the restriction, do not proceed, find an alternative route.
Reduce speed, stay centered in your lane, and approach cautiously, especially if visibility is poor or the road surface is uneven near the structure.