Transport Research International Documentation (TRID) https://trid.trb.org/ en-us Copyright © 2026. National Academy of Sciences. All rights reserved. http://blogs.law.harvard.edu/tech/rss tris-trb@nas.edu (Bill McLeod) tris-trb@nas.edu (Bill McLeod) Transport Research International Documentation (TRID) https://trid.trb.org/Images/PageHeader-wTitle.jpg https://trid.trb.org/ LUMINANCE AND CONTRAST FOR SIGN LEGIBILITY AND COLOR RECOGNITION https://trid.trb.org/View/58795 Thu, 13 Oct 1977 00:00:00 GMT https://trid.trb.org/View/58795 LUMINANCE AND CONTRAST REQUIREMENTS FOR LEGIBILITY AND VISIBILITY OF HIGHWAY SIGNS https://trid.trb.org/View/45716 Sat, 04 Sep 1976 00:00:00 GMT https://trid.trb.org/View/45716