Pub. L. 102-388, tit. IV, sec. 406

Sec. 406. The Secretary of Transportation shall revise the Manual of Uniform Traffic Control Devices to include— (a) a standard for a minimum level of retroreflectivity that must be maintained for pavement markings and signs, which shall apply to all roads open to public travel; and (b) a standard to define the roads that must have a center line or edge lines or both, provided that in setting such standard the Secretary shall consider the functional classification of roads, traffic volumes, and the number and width of lanes.