In North Carolina:
Speed reduction is used for long-term application (i.e., posted regulatory speed limit signs) for work zones where geometry and/or lane width/shoulder width restrictions occur on freeways/expressways/interstates as warranted. The long-term speed reductions are ordinanced by the State Traffic Engineer.
Short-term, temporary speed reductions can be used for worker safety considerations, such as work performed behind drums or cones on high-speed facilities. These short-term speed reductions are signed with changeable message signs and are implemented only when lane closure is in place with workers present. Otherwise, the CMSs will have different work zone information messaging or be turned off. The speed reductions are ordinanced by the State Traffic Engineer.
Work zone speed reductions are normally used on interstates, expressways, or freeways with a posted speed limit of 60 mph or greater.
For long-term speed reductions, NC installs regulatory speed limit signs for reduced speed. For short-term speed reduction, NC uses CMSs.
North Carolina has tried covering speed signs with mixed results.
North Carolina does not use flashing beacons on their signs. Signs normally use orange rigid panels or warning flags on long-term speed limit zones.