markers designating each route shall be erected on the section so incorporated, but no route markers other than standard U S route markers shall appear on any interregional highway, except at points of exit.
Destination signs.—On rural sections of the system, all points of entrance or exit that are located at grade-separated intersections with other highways shall be designated as “interchanges,” and each shall be identified by the name of a single nearby important city or area within a city or by the number of the intersecting highway. Warning of approach to an interchange shall be provided by a sign located at a suitable distance in advance of the interchange, bearing the legend “(Name) interchange ahead.”
At each point of turning at each interchange, a sign shall be provided bearing the name of a single nearby important city or locality served by the intersecting highway with which the particular ramp connects, or the number of the intersecting highway and direction if no geographical name is appropriate, or both if necessary. Immediately beyond the interchange on the interregional highway, a confirmatory U S route marker shall be placed, and also a sign showing the distance to the next important city or interchange. The size, legibility, and location of all such signs shall be appropriate for the conditions of placement and probable speed of traffic on the interregional highway.
Except as above recommended, no direction or distance indications shall be given at interchanges by signs on the interregional highway. Such additional directions and distances as may be deemed desirable shall be indicated by signs located at the junction of the ramp with the intersecting highway.
At interchanges that are lighted at night, all such signs located on the interregional highway shall be illuminated. At other interchanges all signs shall be illuminated where feasible, or if not illuminated, shall be reflectorized.
Signs at grade crossings.—At important grade intersections with other highways, a similar system of signing shall be used on the interregional highway, modified as necessary to indicate also important nearby cities or localities, or highway number and direction, or both, in the direction of permitted left turns as well as right turns. Warning signs preparatory to such turns shall bear the legend ‘“U S (or State) (route number) ahead.” On all highways intersecting interregional highways, appropriate signs and marking shall be installed to provide necessary information for traffic approaching the interregional highway, and to insure the maximum degree of safety to approaching traffic and to traffic on the system.
Where traffic is required to come to a full stop before entering or crossing an interregional highway, a stop line shall be marked on the pavement of the intersecting highway and a standard stop sign bearing the legend “Express highway” shall be erected.
Whether or not a stop sign is required there shall be erected at an appropriate advance location on the intersecting highway a warning sign bearing the legend “Express highway ahead.”
All stop lines shall be reflectorized, and all stop and warning signs shall be illuminated where feasible, and, if not illuminated, shall be reflectorized.
