Abstract: An overhead warning detector. Such detector includes a terminal box positionable on top of a truck cab. A vertically extending fixed member is fixedly positioned with respect to the terminal box. A vertically extending rotatable member is rotatably secured to the fixed member. A bridge feeler extends radially from the rotatable member. The feeler is adjustable in height to an elevation corresponding to the elevational orientation of the highest point of the trailer of the truck. A resilient means interconnecting the fixed and rotatable members tending to hold the bridge feeler in an angle offset forwardly from the vertical but to allow rotation of the rotatable member and feeler rearwardly in response to contact with a low bridge. A control box is positionable in the cab of the truck with electrical leads coupling the fixed and rotatable members. The control panel has an alarm actuatable in response to the rotation of the rotatable member to activate the alarm.