Do not locate overhead sign supports on bridges, if possible. If such location is required, indicate on the bridge layouts a cantilever-type overhead sign support (COSS) founded on a bent cap or on an isolated concrete column on drilled shaft, or an overhead sign bridge (OSB) attached directly to the bridge superstructure. The location of any overhead sign support on bridges requires special design by the Bridge Division.

If overhead support for a dynamic message sign (DMS) is required, determine the appropriate DMS type and its attachment details before completing the detailed project design. Consider whether walkways or light fixtures are required. Configure the DMS on the truss to minimize the horizontal offset between the DMS and the truss. Mount the DMS on a Balanced Tee-type COSS or on an OSB. Do not mount the DMS on a single cantilever-type COSS. Mounting a DMS on an OSB requires a special OSB design by the Bridge Division in addition to the attachment design required if the DMS is to extend over a bridge.

Position sign support brackets for retrofit of signs along existing rails at bridge overpasses such that the bottom edge of the sign panel and support bracket do not encroach on the existing vertical clearance of the bridge.

Do not mount a closed-circuit television (CCTV) on a tube protruding from an OSB or a COSS because of wind or traffic-induced vibrations. These vibrations may be more pronounced when the OSB or COSS is mounted directly to a bridge superstructure.