USE OF CHANGEABLE MESSAGE SIGN (CMS) FOR EMERGENCY SECURITY MESSAGES

The Federal Highway Administration (FHWA) recognizes the value of using changeable message signs (CMS) to convey timely and important information to motorists. State and local transportation agencies have used CMS in times of emergency to convey information to motorists, and ongoing activities related to homeland security may introduce additional opportunities to use CMS. However, messages displayed on CMS must continue to be based on good practice. The purpose of this memorandum is to provide guidance on the use of CMS for displaying emergency or security alert messages. While CMS can be a very effective method of providing information to motorists, they can convey only a limited amount of information and may not be the safest or most effective method in many cases. Therefore, whatever messages are displayed must be readable and understandable by motorists in the amount of time that the CMS can be viewed