High-Low Detector

• Easy-to-use, one-person operation.
• Lightweight aluminum frame construction.
• Vertical-sweep visual indicator.
• Optional simultaneous sound indicator.

The High-Low Detector (Rolling Straight Edge) is used for measuring pavement planeness.

Rolled by one person along a highway, airport runway, or bridge surface, the unit detects, registers, and dye marks high and low areas that need to be ground or re-rolled.

The indicator wheel detects high and low areas in the pavement surface, and a large pointer scale, mounted above the wheel and immediately in front of the steering handle, registers these areas in full view of the operator. Variations are magnified 16 times on a vertical scale graduated in 1/8" (1 mm) increments, so that magnified readings range up to 1/4" (6.4 mm), high or low.

An optional battery-operated 9-volt bell-buzzer located near the operator indicates high and low pavement surfaces simultaneously with the visual indicator.

Upon receiving the visual and audible indicator signals, the operator depresses a button on the steering handle that controls the marking-dye discharge valve. Bright orange dye sprays onto the irregular surface from a replaceable aerosol can mounted directly beside the indicator wheel.