Rolling straight-edge

Measuring device for road straightness

The rolling straight-edge is an instrument used to measure the surface regularity of roads and similar structures such as airport runways. It consists of a straightedge of a fixed distance mounted on wheels with a sensor at the centrepoint measuring deviation in height. It is rolled along the road surface and set to specific trigger levels which can be logged automatically or by means of an audible alarm. The rolling straight-edge was developed by the British Road Research Laboratory to replace earlier manual methods of measurement using rulers. It has been used by several countries and remains in use in the United Kingdom, Germany and Taiwan.

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