To discourage racing, the sign must be programmed to not display speeds that are well in excess of the posted speed limit. Section 2B.18 . Speed Feedback Sign. Example regulatory speed zone application It may be desirable to use the oversize SPEED LIMIT (R2-1, 36x48) sign on conventional highways, in cities or urban areas to emphasize the speed reduction location. From 1930 NCSH Urban Manual. the maximum legal rural speeds are permissible, The R2-1 SPEED LIMIT