Guidelines for the Effective Operation and Control of VDOT Permanent VariableMessage Sign and Highway Advisory Radio Units: State of the Practice and Recommendations

摘要

A variable message sign (VMS), also known as a changeable message sign (CMS), isa programmable traffic control device that can usually display any combination of characters. These signs may be either portable, in which case they can be attached to a trailer and driven to a desired location, or permanent, in which case they are usually installed above the roadway. Highway advisory radio (HAR) units can be used to transmit traffic information to a vehicle's AM radio.