School Advance Warning, Outline
The School Advance Warning assembly should be installed in advance of locations where school buildings or grounds are adjacent to the highway, except where a physical barrier such as fencing separates school children from the highway. The School Advance Warning assembly shall be used in advance of any installation of the School Crosswalk Warning assembly, or in advance of the first installation of the School Speed Limit assembly. If used, the School Advance Warning assembly shall be installed not less than 45 m (150 ft) nor more than 210 m (700 ft) in advance of the school grounds or school crossings. If used, the School Advance Warning assembly shall consist of a School Advance Warning sign supplemented with a plaque with the legend AHEAD or XXX METERS (XXX FEET) to provide advance notice to road users of crossing activity.
Federal Highway Administration Manual on Uniform Traffic Control Devices for Streets and Highways, 2003 Edition (including 2004 and 2007 revisions) (Washington, DC: United States Department of Transportation, 2007)