I don't believe that there are rules.
Hope I helped,
Ms. Weasley
<span>Barricades, vertical panels, drums, and cones in construction zones are known as channelizing devices. They a</span>re used in construction and maintenance work areas <span> to notify drivers or passengers of unusual or potentially dangerous conditions in or near work areas.
</span>A barricade is a portable or fixed device having from one to three rails with appropriate markings. It is used to control traffic by closing, restricting, or delineating all or a portion of the right-of-way.<span>Drums are most commonly used to channelize or delineate traffic flow but may also be used singly or in groups to mark specific locations.</span>
