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
Retaining Wall
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.
Begin Walls
Begin Walls
North
Inside Retaining Wall
Depressed Roadway
Ramp
Outside Retaining Wall
Bridge
Plan View

8. Vertical Scale is Exaggerated! Begin Grade Separation
Vertical Separation
Governor Dr above Genesee Ave
2 inside lanes of Genesee Ave below Governor Dr
A bridge over a depressed roadway
Vertical Scale is Exaggerated!
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. Utility Relocation N 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
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 ADT SB: 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