Sign Standards

• The Federal Highway Administration's "Manual on Uniform Traffic Control Devices" (MUTCD), is the most widely used source of standard road signs in the United States.
  
  

History

• Federal efforts to standardize road signs in the United States began in the early 1900s with the publication of the first edition of the federal MUTCD in 1935. The MUTCD has been revised numerous times since 1935, with the latest revision published in 2009.
  
  

Typical Signs

• Many standard warning signs are commonly encountered--they provide motorists with notice of such roadway features as curves, railroad crossings, traffic signals, merging lanes and dead-ends. Signs sit at standard distances from the roadway feature or hazard, depending on the speed limit of the road.
  
  

Unusual Warning Signs

• Some of the more unusual and least common warning signs in use are for roadway conditions not widely experienced in the United States. For example, there are federally approved warning signs for horse-drawn-vehicle crossings and golf cart crossings. Others warn of the presence of animals including sheep, moose and wild horses.
  
  Some uncommon road signs will become more commonplace as new innovations in transportation engineering expand across the country. Approved warning signs have been developed for roundabouts and traffic circles, railroad crossing quiet (no horn) zones, photo-enforcement, and light rail crossings.
  
  

Experimentation

• Road signs continue to evolve as road situations and technologies evolve. States and municipalities can seek federal approval to test new road signs for specific operating conditions.