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Grade Separation Alternative

Grade Separation Alternative. A Feasibility Analysis of the Reconfiguration of Genesee Avenue at Governor Drive. By: Daniel Aruta, P.E. Topics for Discussion:. What is a Grade Separation? Construction Impacts Traffic Analysis Environmental Impacts. PART 1 : What is a Grade Separation?.

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Grade Separation Alternative

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  1. Grade Separation Alternative A Feasibility Analysis of the Reconfiguration of Genesee Avenue at Governor Drive By: Daniel Aruta, P.E.

  2. Topics for Discussion: • What is a Grade Separation? • Construction Impacts • Traffic Analysis • Environmental Impacts

  3. PART 1: What is a Grade Separation? • A facility which provides a physical vertical separation between two roadways crossing each other to alleviate traffic congestion and promote safety • One roadway passes over another crossing roadway, and both roadways do not meet • The upper roadway crosses over the lower roadway via a bridge • Similar to a diamond interchange on a freeway • A Grade Separation is not a tunnel! University Avenue in Park Slope

  4. Sample of a Grade Separation Diamond Interchange of Interstate 15 at El Cajon Blvd in San Diego El Cajon Blvd Off Ramp Interstate-15

  5. 5 Basic Elements of a Grade Separation Interstate 15 at El Cajon Blvd in San Diego Bridge RetainingWall Retaining Wall Ramp Depressed Roadway

  6. 5 Basic Elements of a Grade Separation Interstate 15 at El Cajon Blvd in San Diego Retaining Wall Bridge Retaining Wall Ramp Depressed Roadway

  7. Genesee Ave Grade Separation at Governor Dr • Bridge on Governor Dr passes over Genesee Ave below • 2 Lanes on Genesee Ave are depressed to pass under the bridge • 4 Ramps • Inside Retaining Walls (4 each) • Outside Retaining Walls (minimum of 4 each) • Total Length from end to end = 1,787 ft. BeginWalls BeginWalls North Inside Retaining Wall Depressed Roadway Ramp Outside Retaining Wall Bridge Plan View

  8. Vertical Separation Vertical Scale is Exaggerated! • Governor Dr above Genesee Ave • 2 inside lanes of Genesee Ave below Governor Dr • A bridge over a depressed roadway Existing Roadway Governor Drive Genesee Depressed Roadway Avenue Begin Grade Separation End Grade Separation Vertical Profile View

  9. Section Through Bridge Section where Genesee Ave passes under the bridge at Governor Dr • Length of Bridge (Span) = > 50 ft. • Width of Bridge = ± 110 ft. Section View

  10. Section Through Retaining Walls Section of Genesee Ave north and south of Governor Dr (beyond bridge) Section View

  11. Lengths of Retaining Walls Inside Retaining Walls: • South of Governor Dr: 731 ft. long, max height greater than16.5 ft. • North of Governor Dr: 936 ft. long, max height greater than16.5 ft. North 731’ 936’ Plan View

  12. Part 2: Construction Impacts • Utility Relocation • Constructing the Bridge • Constructing the Retaining Walls • Road Closures • Environmental Impacts • Project Duration

  13. N Utility Relocation • Two 16” Water Mains • 8” Sewer • Electrical Duct Bank • Gas Line • Phone Cables Water Phone Elect Gas Sewer Governor Dr Water Phone Genesee Ave

  14. Constructing the Bridge • Drive Sheet Piling into the Ground Sheet Piling Section View

  15. Constructing the Bridge • Drive Sheet Piling into the Ground • Excavate Pit for the Bridge Section View

  16. Constructing the Bridge • Drive Sheet Piling into the Ground • Excavate Pit for the Bridge • Construct the Bridge Section View

  17. Constructing the Retaining Walls • Drive Sheet Piling into the Ground • Excavate Channel • Construct Inside Retaining Walls and Depressed Roadway • Construct Outside Retaining Walls for Sideslopes and Outside Roadways Section View

  18. Extent of Sheet Piling in Genesee Ave For Depressed Roadway: Approx. 1,100 ft. each side of depressed road For Outer Retaining Walls: Lengths will vary North Depressed Roadway Sheet Piling Plan View

  19. Environmental Impacts to Consider During Construction Impact • Noise • Vibration • Air Quality • Truck Trips • Contaminated Soils Example • Backup Bells on Construction Equipment • Driving Sheet Piling • Diesel Exhaust from Construction Equipment • Thousands of Truck Trips • Soils Mitigation from 4 Gas Stations – Project Delay

  20. Project Duration • Utility Relocation = 6± months • Mitigation of Contaminated Soils = ? • Construction of Grade Separation = 2± years • Total Project Duration = 2.5+ years

  21. Road Closures during Construction • Genesee Ave from Radcliff La to south of University City HS • Intersection of Governor Dr and Genesee Ave • Disruption to Vehicular and Pedestrian Traffic • Loss of Access to Schools and Businesses • Economic Hardship on Local Businesses • Huge Detriment to the Community North 1,800 ft. Plan View

  22. North/South Access during Construction • No Bridge on Regents Rd • 1,800 ft. of Genesee Ave closed • Intersection of Governor Dr and Genesee Ave closed Police, Fire and Paramedic Service to University City will be severely challenged during construction

  23. Alternate Routes during Construction • Interstate 5 Freeway • Interstate 805 Freeway • State Route 52 Detour!

  24. Part 3: Traffic Analysis – Post Construction • Existing Traffic Movements at Intersection of Genesee & Governor • Proposed Traffic Movements at Intersection of Genesee & Governor • Level of Service and Lane Reductions at Split Points • Elimination of Bus Stops

  25. Existing N-S Traffic Lanes at Intersection • 2 Southbound Through Lanes • 2 Left Turns – SB Genesee to EB Governor • 1 Southbound Right Turn • 2 Northbound Through Lanes • 1 Left Turn – NB Genesee to WB Governor • 1 Northbound Right Turn Existing Intersection

  26. Proposed N-S Traffic Lanes at Intersection • 1 Southbound Combined Through/Right Turn Lane • 1 Left Turn – SB Genesee to EB Governor • 1 Northbound Combined Through/Right Turn Lane • 1 Left Turn – NB Genesee to WB Governor Grade Separation

  27. UC Golden Says: …and… Do The Math:NB: 78% of 33,000 = 25,740 ADTSB: 70% of 33,000 = 23,100 ADT

  28. Street Classification and Level of Service (LOS) • Level of Service “E” = 10,000 ADT for 1 Lane • NB Traffic: 25,740 ADT > 10,000 ADT • SB Traffic: 23,100 ADT > 10,000 ADT NB: 2.57 x Failure Volume SB: 2.31 x Failure Volume

  29. Lane Reduction at Split Point Decision: Do I take the underpass or do I take the ramp to Governor Dr? “Governor Dr ” As most cars from two lanes vie for position into one lane, this will effectively create a “lane reduction” at the split point and traffic will back up! Split Point UC Golden: 1 Through Lane Ramp to Governor Dr

  30. 3 Bus Stops on Genesee Ave are Eliminated Post Construction

  31. Part 4: Environmental Impacts – Post Const. • Noise • Neighborhood Character • Tree Removal

  32. Noise • Sound acoustics are accentuated off retaining walls • Increase in traffic volumes over time due to urban growth will increase ambient noise levels

  33. Neighborhood Character • University City is a residential community • Only small retail except for commercial district on Greenwich Dr • UC is not a major traffic generator like Golden Triangle • Grade Separation will “urbanizes” the character of the neighborhood Should future University City appear like this?

  34. Tree Removal • 88 Conifer Trees • 22 Eucalyptus Trees • 5 Sycamore Trees • 3 Others 118 trees will be removed

  35. The End

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