Dynamic Late Merge System

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Dynamic LateMerge System

• Minnesota Department of Transportation
• DLMS Summary of Experience
• Marthand Nookala
• July 2005Mississippi Valley Conference

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Existing Merging Problems
Mn/DOTs Dynamic Late Merge Study

• Backups extend beyond the farthest advanced
  warning signs when motorists queue up in a single
  lane.
• Traffic flow disruptions and uneven speeds lead
  to rear-end accidents.
• Erratic merging along the entire length of the
  traffic queue during congested conditions.
• Increased Road Rage

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This scenario commonly occurs duringlane closures
Mn/DOTs Dynamic Late Merge Study
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Preferred Traffic Flow UtilizingEqual Lane
Occupancy
Mn/DOTs Dynamic Late Merge Study
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DLMS Basics
Mn/DOTs Dynamic Late Merge Study

• Purpose of the system is to provide guidance to
  motorists on proper lane usage
• When traffic is free-flowing, the standard lane
  closure signage has always been adequate
• When traffic volume increases, motorists tend to
  merge early to the thru-lane and create a long
  queue in one lane, affecting safety and upstream
  intersection operation.

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DLMS Basics Continued
Mn/DOTs Dynamic Late Merge Study

• The DLMS sensors determine when the traffic is
  approaching congestion level
• Upstream PCMSs are activated when traffic exceed
  threshold levels
• Messages on the PCMSs warning motorists of the
  STOPPED TRAFFIC AHEAD and instruct them to USE
  BOTH LANES and MERGE AHEAD.
• Near the lane closure taper, the PCMSs instruct
  the motorists to MERGE HERE

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Typical DLMS Setup
Mn/DOTs Dynamic Late Merge Study

• Used In Addition to the Standard Traffic
  Control
• Easy Trailer Mounted PCMS Deployment and
  Fast Adjustments
• PCMS only used during congested periods and
  remain Dark during free- flow conditions

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1st Sign Approximately 3 miles upstream
Mn/DOTs Dynamic Late Merge Study
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2nd Sign - 1.5 miles from Taper
Mn/DOTs Dynamic Late Merge Study
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3rd Sign Located at Taper
Mn/DOTs Dynamic Late Merge Study
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DLMS Basics Continued
Mn/DOTs Dynamic Late Merge Study

• When congestion levels return to free-flow the
  PCMSs return to dark mode
• Motorists resume normal merging practices and
  safely merge based upon speed and traffic volume

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Four DLMS Study Locations
Mn/DOTs Dynamic Late Merge Study

• Urban locations
• Hwy 10 in Anoka (2003)
• Hwy 494 in West Metro
• Hwy 52 at Lafayette Bridge
• Rural location
• I -35 from north of Faribault to Lakeville

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Project Coordination
Mn/DOTs Dynamic Late Merge Study

• Mn/DOT Construction and Traffic Offices
  coordinated the study.
• Input and cooperation from field.
• Traffic Tech., Inc. provided the Dynamic Late
  Merge System.
• URS Inc. collected data and provided the final
  research report.

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DLMS Potential Benefits
Mn/DOTs Dynamic Late Merge Study

• Reduced traffic conflicts and crashes
• Reduce Aggressive Driving and Road Rage
• Reduce the number of early merges during
  congested conditions
• Shorten Queue lengths
• Increase capacity and reduce travel time

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Before and After Deployment
Mn/DOTs Dynamic Late Merge Study
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Findings and Results
Mn/DOTs Dynamic Late Merge Study

• Accidents seem to be reduced
• Queue Lengths were reduced by 40
• Lane occupancy increased everyday during
  congestion - reached near equal lane occupancy
  after short duration
• Less confusion and reduced aggressive driving

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Guidance on When to Use
Mn/DOTs Dynamic Late Merge Study

• Lane closures from 2 lanes down to 1
• Hourly Volume exceeds 1500 vehicles for at least
  2 hours per day
• Lane Closure will be in place for at least three
  days
• These guidelines are preliminary and will be
  adjusted with more experience

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DLMS Acceptance
Mn/DOTs Dynamic Late Merge Study

• Many positive comments from field project
  personnel, motorists and the media
• State Patrol has been very supportive
• Since the first deployments, many motorists have
  requested that the system be utilized on more
  projects

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System Costs
Mn/DOTs Dynamic Late Merge Study

• Detection approximately 300 per day3 PCMS cost
  600 per daytotal of 900 per day per direction
• System costs generally total 1 3 of overall
  project costs

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Future use of Dynamic Merge
Mn/DOTs Dynamic Late Merge Study

• Expanding the use of these systems on a number of
  projects this construction season.
• Including as a pay item in construction projects.
  
• Also require the vendor to be on QPL.
• As vendors increase, cost will drop

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QuestionsDLMS Study Report Available
Onlinewww.dot.state.mn.us/trafficeng/workzone
Mn/DOTs Dynamic Late Merge Study
Minnesota Department of Transportation DLMS
Summary of Experience Marthand Nookala July
2005Mississippi Valley Conference