1. October 8, 2008 Spokane, WA Doug Walters, P.E. King County DOT
Sunday Creek Bridge Replacement Utilizing Geosynthetic Reinforced Soil (GRS) Abutments
October 8, 2008
Spokane, WA
Doug Walters, P.E.
King County DOT

2. Project Location

3. Existing Log Stringer Bridge

4. Bridge Deck

5. Typical Bridge Traffic Prior to Load Restrictions

6. Deficiencies Structural Environmental
Timber cribbing abutments & log stringers damaged
Minor scour
1997- Placed temporary shoring
load limit of 3 tons
Environmental
Cited by the WA Department of Fish and Wildlife
Temporary shoring within stream channel

7. West abutment temporary shoring
I-Beam on Ecology Blocks

8. East Abutment Temporary Shoring
Shoring Support

9. Typical rot on log stringers

10. Superstructure: Prefabricated Steel Truss

11. Superstructure Selection
Hydraulic Opening
Above 100 year flood elevation
Changing road grade
additional environmental permitting
Narrow Haul Road

12. Superstructure: Prefabricated Steel Truss
3ft clear space 12

13. Foundation Considerations
Borings
Alternating layers of medium dense alluvial gravel, sand, and silt
Abutment Foundation
Shallow foundation
Base of foundation below stream’s thalwag elevation
Sheet Pile Cutoff Walls
Allow dry construction
Provide additional scour protection

14. GRS Abutment Selection
Constructability
Avoid long concrete haul
Not weather dependent
Reduced time of construction
Cost Savings
Materials
General labor
Standard equipment
Environmental
No concrete placement

15. GRS Abutment Design Outline
King County preliminary GRS abutment
NCHRP Report 556 “Design and construction of GRS abutments”
Mike Adams (FHWA) reviewed & refined design
Provided GRS design detail with layout
continue to provide evaluation, design, and construction support

16. BRIDGE LAYOUT
22 ft
104 ft
PLAN
14 ft
25 ft

17. GRS ABUTMENT DETAIL
FINISHED GRADE LINE

18. CMU Block Schedule
36 ft
23 ft
5 ft
9 ft
11 ft
11 ft

19. Tasks to be completed Finalize Design Bid January 2009
Construction June 2009

20. THANK YOU! Question?