Evaluation of retroflective sheetings for use on roadway traffic signs (FHWA-OK-95-02) 2193

Abstract

The primary objectives of this research were to evaluate the ODOT's policy on use of retroreflective sheeting products, and to identify any necessary changes to this policy based on driver visibility needs, durability of sk.eting materials, life-cycle cost, and other practical considerations. 1be scope of the study included three types of retroreflective sheetings (engineering grade, super-engineering grade. and encapsulated-lens highintensity sheeting), five sheeting colors (white, red, yellow, green. and blue) , and two sign fabrication metOOds (screening and overlay). To meet the objectives of this project, a research plan consisting of literature review, controlled field experiments, survey of ODOT field divisions, durability data collection and analysis, and lifecycle cost analysis was adopted. 1be findings of this study suggest that the specification of type ill-A (high-intensity, encapsulated glassbead sheeting) on all red and yellow signs, as well as green and blue signs on interstate highways and freeways is soum and defensible. 1be requirement that type II-A (super-engineering grade sheeting) be used on all other traffic signs, except orange colored signs, needs to be examined. Altlx>ugh the initial cost of sign face fabrication for type-mA sheeting is 25% to 65% higher than that of type-II.A, life-cycle cost analysis indicates that type-mA is more cost-effective than type-IIA Evidence from visibility distance analyses and subjective evaluations made by the test subjects suggests that, in addition to upgrading sign materials to provide greater luminance, larger sign size and letter size are needed to satisfy the minimum required visibility distances, particularly at high speed, high traffic volume, and high visual comp lexity locations.