Vermont state highway signs are replaced on a systematic basis on a 15-year cycle in order to continue to meet national standards. These standards include: sign spacing, shape, color, retroreflectivity and text size and spacing requirements. Traffic signs are regulated by the Federal Highway Administration's (FHWA) Manual on Uniform Traffic Control Devices (MUTCD). Compliance with the MUTCD ensures that drivers from any State will be familiar with the size, type and location of traffic signs no matter where they travel within the United States. Vermont State Statute requires that traffic control devices on all Vermont public roads adhere to the MUTCD.