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GDOT’s Metro Atlanta Ramp Meters

GDOT’s Metro Atlanta Ramp Meters. Marc Plotkin Traffic Engineer II :Regional Traffic Operations. Topics. What, and Why Safety Benefits Design Considerations History in Atlanta Implementation Operations Results and Findings. What Are Ramp Meters.

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GDOT’s Metro Atlanta Ramp Meters

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  1. GDOT’s Metro AtlantaRamp Meters Marc Plotkin Traffic Engineer II :Regional Traffic Operations

  2. Topics • What, and Why • Safety • Benefits • Design Considerations • History in Atlanta • Implementation • Operations • Results and Findings

  3. What Are Ramp Meters • Part of NaviGAtor, Georgia DOT’s Intelligent Transportation System (ITS) • “Traffic lights” on interstate entrance ramps designed to control traffic flow onto the interstate • Proven to relieve traffic congestion in over 20 U.S. cities for over 20 years

  4. Ramp Meter Locations

  5. Why? • Reduces crashes at merge points • Increases freeway productivity • Reduces stop-and-go traffic • Reduces fuel consumption • Cost-effective traffic management tool • Improves trip predictability

  6. Safety Analysis Minnesota • Ramp Meter shutdown test • With Metering 261 crashes • Without metering 476 crashes • Annual Savings from metering • Property damage only • $4.8 million • Injuries • $6.8 million • Fatalities • $6.6 million

  7. 43% Portland, OR 20% Los Angeles, CA 38% Seattle, WA 26% Minneapolis, MN 15% Long Island, NY Reduction in Crashes

  8. Benefits of Ramp Meters PREPARE TO STOP • Improved traffic flow from surface street to freeway • Faster travel times • Reduced merging accidents • Reduced fuel consumption • Reduced vehicle emissions

  9. Design Considerations • Some ramps dropped out of consideration during design phase • “slip” ramps – such as I-85 frontage road system • Ramps with very short storage • C/D ramps • No “geometrical” changes allowed • No widening • Some striping changes allowed if shoulders maintained • Acceleration distances • AASHTO Green Book compliance maintained

  10. History of Ramp Meters in Atlanta Begin Phase II –the Modern Years • Preparation for Olympics in 1996 • Congestion was back, relief needed and capacity was fixed • Pilot project – 5 ramps selected • Meters began operation December 1996 • Low impact ramps were selected for the pilot: • No widening/extending • Single lanes • Not a big residential area • Relatively low volumes

  11. Downtown Atlanta 1967 – Atlanta History Center

  12. Ramp Meter Pilot I-75 NB • Meters programmed to turn ON at 3:45 PM weekdays (TMC Planning) • Loop Detection with 3 second gap • Max rate set on the fly • Minimize delay on ramp (adjust rate) • Longer ramps = Adjust rate up • Shorter ramps = Adjust rate down • Meter ramps as needed on individual basis • Base rates on various time of day schedule

  13. History of Ramp Meters in Atlanta Phase III – the ‘Fast Forward’ years (2006-2012) • GDOT elected to go “all in” • Funding mechanism, Governors’ “Fast Forward” program • 18 year worth of congestion-relief projects in 6 years • Included 165 more ramp meters • Staged installation, one freeway at a time

  14. Meters on as of January 2009 GA 400 I-85 I-75 I-20 I-20 I-75 I-85

  15. Meters on as of January 2010 GA 400 GA 400 I-85 I-85 I-75 I-75 I-20 I-20 I-20 I-20 I-75 I-75 I-85 I-85

  16. Georgia Ramp Meter System Today GA 400 I-75 I-85 I-20 I-85 I-75

  17. Current Ramp Meter Locations • 185 Ramp Meters: • Original 5on I-75 NB, Midtown to Cumberland Mall (1996) • 27 Locations on I-20 • 51 Locations on I-285 • 8 Locations on I-575 • 40 Locations on I-75 North and South of Atlanta • 15 Locations on the 75/85 Connector • 19 Locations on I-85 • 2 Locations on the Buford Connector • 15 Locations on GA 400 • 8 Locations on US 78

  18. Operations- GDOT Mindset GDOT’s goal: partner with locals to provide the best possible travel time for the public. best = more consistent and reliable Ramp meter’s objective: Aid the mainline while limiting the impact from arterial networks supplying demand. How do we do that? • Providing consistent flow for merging vehicles Resulting in improved • Mobility • Safety

  19. Operations – Day to Day Queue Management • Making sure that arterials aren’t negatively impacted How do we do that? • Remote monitoring – during peaks • Navigator 2 • Centrally connected system • Threshold adjustments • Speed up metering • Shut down • Ramp • Mainline (Testing)

  20. Queue Management WITH … WITHOUT …

  21. Results 285 Westbound – PM peak – from Chamblee Dunwoody to I-75 (9 Miles) Travel Time reduced 6 Minutes

  22. Results 285 Eastbound – PM peak from Roswell Rd to I-85 (8 Miles) Travel Time reduced 5 Minutes

  23. Result Summary • Travel time reductions ranged from: • 50 seconds to 6 minutes • 8 – 35% • # of stop reductions ranged from: • 0.7 to 5.3 • Total delay reductions ranged from: • 30 seconds to 5 minutes • 11 to 82%

  24. Result Summary • Emissions data was also collected • Hydrocarbon (g) reductions ranged from: • 5 to 31% • Oxides of Nitrogen (g) reductions ranged from: • 5 to 38% • One corridor increased 6% • Carbon Monoxide (g) reductions ranged from: • 1 to 15% • Two corridors had increases (1% and 13%)

  25. I-285 Westbound PM Peak

  26. Thank you • Marc Plotkin • Traffic Engineer II • mplotkin@dot.ga.gov

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