Conflict Warning Systems can include all of the following:

  • Work Space Intrusions
  • Speed Feedback Signs
  • Over Dimension Warnings
  • Excessive Speed Warnings
  • Haul Road Intrusions
  • Trucks Entering, Exiting or Crossing

DEPLOYMENT CRITERIA CONSIDERATIONS:

A Conflict Warning System should be considered for deployment as part of a project’s temporary traffic-control plan when the following conditions are anticipated:

  • Workers will be located adjacent to the open traffic lane.
  • Hazardous roadway conditions require extra driving precautions.
  • Construction causes minimal clearance (or less than minimum) for large vehicles using the roadway.
  • Traffic must reduce speed to safely negotiate a hazardous condition such as an unusually tight curve or rough road surface.
  • Trucks exiting the traffic flow at approximately highway speed have a deceleration lane prior to entering the haul road or must utilize the mainline roadway to decelerate.
  • The roadway volume is above the level where the traffic must suddenly adjust speed or change lanes, or roadway volume causes vehicles to tailgate the trucks so drivers may inadvertently follow a truck off the roadway.
  • The ADT on the roadway is above the level where truck drivers can easily find a gap in traffic and adjust their crossing time to fit with traffic, but below a level where gaps are difficult to find in traffic.
  • Trucks must utilize the mainline roadway to accelerate.
  • A truck merge lane cannot be provided on the project.
  • The haul road entrance is visibly obscured to drivers.
  • The ADT on the roadway is above the level where truck drivers can easily find a gap in traffic and accelerate within the traffic lane without causing traffic to suddenly adjust speed or change lanes.

ANTICIPATED SYSTEM EFFECTS:

When properly designed and deployed for a specific project, a Conflict Warning System should be able to alert drivers (and construction workers) of many dangers and conditions and allow them to adjust accordingly, including:

  • A slowly accelerating truck is entering the faster-moving traffic lane.
  • Truck traffic on a temporary haul road is crossing the roadway.
  • A decelerating truck is exiting the faster-moving traffic lane.
  • They have inadvertently followed a construction truck into the construction zone.
  • They have inadvertently entered a portion of the work zone at a speed substantially above the advisory speed limit.
  • The construction is causing minimal clearance (or less than minimum) for large vehicles using the roadway.
  • A minimal clearance condition exists within a work zone (for construction vehicles).
  • The vehicle is over-dimension, and they are required to use an escape route.
  • Their current speed is higher than the advisory speed for the situation.

ADDITIONAL RESOURCES:

Deployment criteria and anticipated effects are suggestions that were provided by the MnDOT 2007/2008 report “Minnesota Intelligent Work Zone Toolbox.”