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/ DETECTION OF VOIDS UNDERGROUND AND UNDER PAVEMENTS https://trid.trb.org/View/63246 Sun, 16 Jan 1977 00:00:00 GMT https://trid.trb.org/View/63246