Which marker is required to be at least 18 inches high and 2 inches wide?

The requirement for a marker to be at least 18 inches high and 2 inches wide is specific to tubular markers. Tubular markers are often used to guide or delineate pathways, especially in work zones or areas where visibility might be impaired. Their height and width dimensions ensure that they are easily noticeable to drivers and pedestrians, increasing safety by providing clear visual cues.

In comparison, other types of markers may serve different purposes or be subject to different specifications regarding size. For instance, warning markers typically serve as alerts for hazards but do not have a standardized height and width requirement of this nature. Flashing markers often indicate active hazards or require attention but also do not carry specific size mandates like tubular markers. Reflective markers are designed to enhance visibility at night or in adverse conditions but are not defined by the same dimensions as tubular markers.