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James P McCarthy, PE PTOE Minnesota Division 651-291-6112

Superstreets “A Tool for Safely and Efficiently Managing Traffic” Alternative Intersections – on High Volume Arterials. James P McCarthy, PE PTOE Minnesota Division 651-291-6112. The Superstreet. Distinguishing Feature:

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James P McCarthy, PE PTOE Minnesota Division 651-291-6112

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  1. Superstreets“A Tool for Safely and Efficiently Managing Traffic”Alternative Intersections – on High Volume Arterials James P McCarthy, PE PTOE Minnesota Division 651-291-6112

  2. The Superstreet

  3. Distinguishing Feature: Left-turn movement (on one or more approaches) strategically relocated to the far-side of the opposing roadway via interconnected signalized crossover in advance of the main intersection DLT SR 30 and Summit Rd in Fenton, MO Source: Bing

  4. DLT • Interchange footprint vs. DLT footprint • Effects on built environment • Interchange cost vs. DLT cost • Capacity vs signal?

  5. MUT • Corridor Capacity increases 20-50% • 2 phase signal creates better progression-large “green bands” without very long cycles

  6. Signalized RCI • Mainline Traffic Benefits • Sidestreet Benefits? • Ped Benefits

  7. Why Superstreets?

  8. Answer: • Less Travel Time / Greater Capacity • Economically Beneficial • Improved Safety • Environmentally Responsible

  9. Why Superstreets? Less Travel Time • Reduced “wait time” or delay • Increased roadway capacity Less Travel Time

  10. Less Travel Time

  11. Main Street Green Time 4 Bad 2 Good Less Travel Time

  12. Project Example – Intersection Performance • Standard Intersection • Alternative Intersection • Using Cap-X Screening Calculation

  13. Why Superstreets? Economically Beneficial • Preserves the existing facility • Less expensive than an interchange • Provides good access to both sides of the main road for development Economically Beneficial

  14. Economically Beneficial

  15. Economically Beneficial

  16. Corridor Impacts

  17. Why Superstreets? Improved Safety • Reduced likelihood of crashes, especially severe crashes such as side-collisions • Fewer threats to crossing pedestrians

  18. Reduction in Crashes • Safety impact by collision type for unsignalized superstreets, % Improved Safety

  19. Median U-Turn Intersection MI Safety Experience Grand River Ave. • Replaced conventional signalized intersections • 60% reduction in total crash frequencies • 75% reduction in total injuries • Reduction by type • (17%) rear-end crashes • (96%) angle crashes • (61%) side-swipe crashes

  20. Safety Conclusions Improved Safety • Unsignalized superstreets: • Reduced collisions for total, angle and right turn, left turn, and fatal and injury • Total collisions reduced by 46% (C-G method) • Reduction of Fatalities goes to local users (those on minor road)

  21. Are U-turns safe?

  22. Accidents related to U-turn and left-turn maneuvers at unsignalized median openings occur very infrequently… The 12 median openings in rural arterial corridors evaluated in detail in this research experienced an average of 0.20 accidents per median opening per year… Based on these limited accident frequencies, there is no indication that U-turns at unsignalized median openings constitute a major safety concern.

  23. Environmentally Responsible Why Superstreets? • Less time spent idling at a red light • Reduction in environmental pollutants • (exhaust fumes / fuel usage) • Less acreage impacted by construction • and permanent facility

  24. Environmentally Responsible Why Superstreets? • Superstreets support a sustainable transportation program • A well designed super street will provide better and safer pedestrian and bicycle accomodates than a standard intersection

  25. Non-Auto Features

  26. Can Superstreets Accommodate Semi-Trailer Combinations?

  27. ABSOLUTELY!

  28. RCI – O Signals, 1 Signal or 3 Signals? Unsignalized

  29. Signalized RCI

  30. Superstreets in North Carolina • Selected Existing Locations • US 15/501 in Chapel Hill, Orange County (Signalized) • US 17 in Pender & New Hanover Counties (Signalized) • US 17 in Leland, Brunswick County (Signalized) • US 23-74 in Haywood County • US 1 in Moore County, Vass Bypass • NC 87 in Elizabethtown, Bladen County • US 601 in Union County • US 17 By-Pass in Martin and Beaufort Counties • Super Streets in Minnesota ?

  31. US 281 (San Antonio TX) 2009 – Looking south above Evans Road, PM peak

  32. 4 Bad 2 Good

  33. US281 Superstreet Comments As traffic congestion on U.S. Highway 281 eases due to the completion of the superstreet project, construction of new commercial and retail developments along the far North Central San Antonio corridor is ramping up. “We are close to 90 percent leased with no pad sites left,” Elliott remarked. “We've had quite a bit of interest because of the market, which is in a high growth area. And a lot of our tenants say they feel like business has increased since the superstreet was finished.” San Antonio Express-News March 17, 2011

  34. Superstreets A tool for improving Interregional Corridor and Twin Cities Expressways

  35. Strategic Highway Corridors • Map of Minnesota Expressways • Map of Metro Expressways

  36. Summary of Superstreet Benefits • Safety • Time savings • Increased capacity • Improved traffic flow • Access management • Land use and corridor protection • Alternative to interchange (Less $$$) • Smaller “footprint” than an interchange

  37. Thank You!Jim McCarthy 651-291-6112Will Stein 651-291-6116

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