SIGN VARIABLES or VARIABLE MESSAGE SIGNS
Variable Message Signs (VMS) are used to inform and direct motorists of variable situations in a consistent and orderly manner. The messages are meant for:
- Traffic control
- Management and
- Timely traveller information
Critical aspects of these traffic control devices are:
- Legibility
- Reliability and
- Credibility
- The signs are designed to modify motorist behaviour to improve traffic flow and operations.
- Information for travellers is displayed due to a planned or unplanned event which is scheduled by operations personnel.
- They are commonly installed on full span overhead sign bridges, post-mounted roadway on shoulders, overhead cantilever structures and portable types mounted on trailers/prime-mover.
- Below are a few examples on information provided through VMS
- Travel time between known destinations
- Congestion conditions along a high-speed corridor
- Construction site warnings / Information notices
- Special event notice and motorist instructions
- Maintenance operations schedule
- Severe weather announcement
- Incident or accident information
- For all information displayed, the goal is to have a positive impact on the motorist's travel time
- The system comprises of continuous and discontinuous signs
- Variable Message Signs (VMS) used for dynamic traffic management are of discontinuous type and make use of ligh emitting techniques (Ex: Fiber optic or LED signs)
- VMS for a part of Advanced Traffic Management System (ATMS) which is one of the major components of ITS (Intelligent Transport System)
- The integrated ATMS software receives online data from Automatic Traffic Counter and Classifier (ATCC), meteorological sensors, Traffic Control System, CCTV, Video Incident Detection System (VIDS), Emergency Call Boxes (EBC), etc.
- This data is processed and analysed. The information is then shared with road users through VMS, SMS, FM, radio, etc.
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