BS 873 was first published in 1939 in response to a request from the Association of Road Traffic Sign Makers, and was revised in 1959 and 1970. As a result of subsequent experience and the advent of new materials and methods of construction, it is being further revised to bring it up-to-date. This process will continue in future revisions. A sign normally consists of a legend carried by a sign face which may be of sheet or other applied material (e.g. paint or print) mounted on a substrate and fixed to a frame and supported by a post or posts. Other types of signs (e.g. traffic cones) may be of more simple construction and self supporting.
This Part of BS 873 defines general terms and describes photometric tests for internally and externally illuminated signs and for the coefficient of retroreflection for retroreflective materials. It also describes the methods of testing signs and luminaires or their components for resistance to impact, wind pressure, dirt and corrosion. Tests for bonding sheet sign face materials and for the efficiency of bond of superimposed solid glass beads are also described.
Requirements for the various elements and signs are laid down in the further Parts of this British Standard, which generally refer back to the test methods described in this Part.