Stiff but bendable elongated plastic article

Claim 1

A highway delineator comprising an extruded elongated article which displays substantial resistance to bending or twisting but can be bent 90° across its longitudinal axis and across the plane of juncture of its faces without suffering significant plastic deformation, said article (1) being constructed of a thermoplastic aromatic polycarbonate which (a) can sustain an elastic strain of in excess of about 5%, and (b) displays a notched Izod impact strength of at least about 5 ft-lb. at room temperature in a 1/8" specimen, (2) having the shape of two sheets which (a) each has two parallel longitudinal edges, (b) each has the configuration of an arc with wings in its shorter dimension, (c) are joined to each other along both of their longitudinal edges, (d) define a lens shape in the cross-section perpendicular to their longitudinal axis which has a width between about 2 and 4 times its height and has wings extending in the plane of juncture of these sheets for a distance of between about 0.25 and 0.75 times the width of the lens shape, and (e) each has a reverse curvature at both of its longitudinal edges just before the point of juncture of a radius both at least about fifteen times the thickness of the sheet and sufficient to allow its interior surface to meet the interior surface of the other sheet without significant plastic deformation when the article is bent 90° across its longitudinal axis and across the plane of said juncture, and (3) being able to withstand the impact of a vehicle bumper at 50 miles per hour which causes it to bend 90° across its longitudinal axis and across the plane of juncture of these sheets.