Federal Highway Administration page has links to the Highway Standard Plan Drawings of the States:
Brother Schmidt
Thanks for the link! I dug down to the Nevada DOT standards for grade crossings. Very interesting. On a 75mph road, the advance warning sign (circular yellow with black markings) is supposed to be 650 feet in advance of the stop line at the crossing. Minimum distance on roads with lower speed limits is 100 feet. Methinks a bit of selective compression would be needed on most layouts…
Chuck (Modeling Central Japan in September, 1964)