Variable Message Signs Boost Safety on Construction Roads

Imagine driving on a highway when sudden road construction appears ahead. Without clear guidance, confusion would likely ensue. This is where Portable Changeable Message Signs (PCMS) prove invaluable. Acting as "information commanders" of the roadway, they display real-time traffic updates to guide motorists safely through changing conditions.

Portable Changeable Message Signs (PCMS) are temporary traffic control devices distinguished by their flexibility. These electronic displays function similarly to digital billboards, except they convey critical traffic information rather than commercial advertisements.

While PCMS generally follow the same design and application principles as permanent changeable message signs, they operate under specific regulations that warrant closer examination.

PCMS serve numerous functions within Temporary Traffic Control (TTC) zones:

• Road/lane/ramp closures: Alert drivers to upcoming closures and suggest alternate routes
• Incident management: Provide accident notifications to prevent secondary collisions
• Width restrictions: Warn oversized vehicles about narrow passages
• Speed adjustments: Recommend appropriate speeds for current conditions
• Construction notices: Inform motorists about work zones and potential delays
• Traffic diversion: Guide drivers to alternate routes during congestion
• Weather/event alerts: Broadcast warnings about hazardous conditions
• Operational controls: Manage lane allocations during peak periods

Essentially, PCMS prepare drivers for unexpected roadway situations through timely notifications.

PCMS offer three primary benefits over static signage:

1. Detailed messaging: Capable of displaying complex information including accident causes, congestion levels, and estimated clearance times
2. Real-time updates: Continuously refresh to reflect current conditions
3. Decision support: Enable better driving choices regarding route selection and speed adjustment

Typical PCMS applications include:

• Warning of significant speed reductions
• Alerting to severe queuing and delays
• Broadcasting adverse weather conditions
• Notifying of roadway geometry or surface changes
• Announcing upcoming closures
• Managing accident scenes
• Indicating changes in road user patterns

A complete PCMS unit consists of:

• Information display panel
• Control system
• Power supply
• Mounting/transport equipment

Display surfaces typically feature protective coverings for durability.

Effective PCMS operation requires adherence to established guidelines:

• Compliance with manuals like the Manual on Uniform Traffic Control Devices (MUTCD)
• Exclusive use for traffic-related messages (no commercial content)
• Clear, unambiguous wording
• Standard-compliant color schemes (e.g., yellow/orange for warnings)
• Appropriate brightness levels (visible by day, non-glaring at night)
• Minimum 800-meter daytime visibility
• Concise messaging (avoiding information overload)
• Minimum 45cm character height
• Static displays (no animations or scrolling text)
• 2-8 second message durations for multi-phase displays
• Logical message structure: situation → location → recommended action
• Proper spacing between multiple signs (300m for highways, 150m for local roads)
• Standardized abbreviations when needed
• Automatic brightness adjustment
• Control systems with preview capability and memory retention
• Backup power provisions
• Proper mounting heights (2.1m urban, 1.5m rural)

Additional usage guidelines include:

• Supplemental role (not replacing standard signs/markings)
• Adequate advance placement for diversion notices
• Strategic positioning for maximum visibility and reaction time
• Shoulder placement with protective barriers when possible
• Exclusive display of traffic control messages in TTC zones
• Proper storage when inactive (moved outside clear zones or oriented away from traffic)
• Reflective markings on trailers for nighttime visibility

Portable Changeable Message Signs have become indispensable tools in modern traffic management. By delivering real-time roadway information, these electronic sentinels enhance safety and efficiency for all travelers. Their strategic deployment and proper operation contribute significantly to smoother journeys and reduced congestion.