Devices and early warning methods used to reduce hits on low-clearance structures

TxDOT has used high-load detection systems around the state. One system consists of a laser transmitter and receiver installed at clearance height on each side of the road. When the beam is broken by an overheight vehicle, the system activates an advance flashing beacon assembly with warning sign. This system seems to work well.

Another system they use is a drop-tube warning device. This system consists of an overhead set of aluminum alloy drop-tubes placed across the road attached to a guy wire. A sign which reads, “If You Hit This You’ll Hit Bridge” is placed above the drop tubes. An advance warning sign, “Load Height Gauge Ahead,” is placed to warn motorists of the drop tubes ahead.