According to the MnDOT IWZ Toolbox, a Dynamic Lane Merge System (DLMS) can either be a “Dynamic Late Merge” or a “Dynamic Early Merge” system. According to MnDOT, these systems should be considered for deployment as part of a project’s temporary traffic-control plan when any of the following conditions are anticipated:

  • A high hourly traffic volume causes a queue of traffic before the merge area for at least two hours per day. Typically, this volume must exceed 1,500 vehicles per hour to cause large queues.
  • During congested periods when the estimated traffic queue lengths (without the DLM system implemented) may encroach on upstream intersection/interchange operations.
  • The speeds and lane occupancy volumes are anticipated to vary unpredictably causing the motorist to have trouble identifying the best lane-usage practice, such as using both lanes versus moving into the continuous thru-lane.


The system should alert drivers of an upcoming traffic slow-down or stopped traffic, and inform them to use both lanes until the designated merge point. It is anticipated that the system will reduce the length of the upstream queue by 40%, which may reduce conflicts at nearby intersections. By utilizing both traffic lanes, the differential speed between lanes is greatly reduced since both lanes travel at approximately the same speed. Motorists are given positive directions on lane usage and merging, which clears misunderstandings between drivers and reduces road rage.

Minnesota DOT captured a great example of the Dynamic Lane Merge’s effectiveness:

Our friends at the Wisconsin DOT made this great video to further explain the proper process of the Dynamic Lane Merge


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