These are guide signs that are typically used along urban freeways with closely spaced interchanges. As per Federal guidelines, the installation of these signs is optional. When used, this type of sign should be used over the entire length of a route in an urban area. Signs should also be used in place of Advance Guide signs if there is less than 800 feet between exits. Additional information on their use can be found on page 223 of the 2009 Manual on Uniform Traffic Control Devices (MUTCD).