Hydraulic Design of New Woodrow Wilson Bridge

1. Hydraulic Design of New Woodrow Wilson Bridge

2. Hydraulic Design of New WWB Location of Woodrow Wilson Bridge

3. WWB bridge carries I-95 & I-495 over Potomac R. Opened in 1961 Designed for 75,000 VPD Today >190,000VPD 300,000 VPD by 2020 Owned by FHWA Located in VA, DC and MD Hydraulic Design of New WWB

4. Existing bridge 5,900 ft long 58 spans Four leaf bascule span Functionally obsolete Deck on Bascule Spans beyond fatigue life New bridge under design Hydraulic Design of New WWB

5. New bridge 6052 ft long 2 parallel bridges 18 spans 8 leaf bascule span Pile supported footings Capacity 300,000 VPD Estimated cost ~ $2B Hydraulic Design of New WWB

6. Hydraulic Design Process “Concepts Worth Discussing” • Scour Team • Organization & Coordination • Hydrology • Computer Models • Physical Models • Scour in Cohesive Soils • Final Recommendations

7. The Scour Team Final recommended scour depths and pier geometry were determined by a team of hydraulic, structural and geotechnical engineers .

8. The Scour Team • Represents a wide area of knowledge and experience • Provides opportunity to apply state-of -the-art methodologies • Provides opportunity for periodic review and discussion of different methodologies • Team serves as decision maker for complex issues or where there is a divergence of viewpoints

9. Hydraulic Design of New WWB Coordination & Communication • General Engineering Consultant/Subs • Design Consultant/Subs • FHWA and State DOT’s • University and other Research Engineers • Structural Concerns • Geotechnical Concerns • Hydraulic / Scour Concerns • Coordination & Communication of Decisions

10. PIER DESIGN PROCESS

11. Hydrologic Design of New WWB • HYDROLOGY • Drainage area at bridge site 11,860 sq. mi. • Tidal influence at bridge, ~ 3 ft range day • Q100 = 480,000 cfs • Q500 = 700,000 cfs Potomac River Basin

12. HEC-RAS Analysis performed for Q100 and Q500 10 Cross sections surveyed Boundary conditions defined by flood records n based on previous calibration study by Corps of Engineers Hydraulic Design of New WWB

13. Tidal analysis of river performed for Q100 and Q500 using Maryland Tidal Analysis Program (based on the Neill method) and studies by the University of Maryland. Hydraulic Design of New WWB

14. Hydraulic Design of New WWB Local velocities for scour analysis determined by conveyance subdivision.

15. Hydraulic Design of New WWB Modeling of Energy Losses at Piers. Wide piers modeled as blocked obstructions

16. SMS-Flo2DH Analysis performed for Q100 and Q500 Ground & River elevations from 30 m DEM’s and Estuary database n adjusted to match 1-D upstream WS Elevation Hydraulic Design of New WWB

17. Hydraulic Design of New WWB Local velocities and angle of attack for scour analysis obtained directly from 2-D output.

18. HEC-18 with wide pier modification (using local velocities from 1-D & 2-D Models ) FHWA Equations for complex piers Enhanced CCHE 3-D Model Physical Models (large and small scale) Scour in cohesive materials Abutment Scour Vertical and Lateral Stream Stability Risk Assessment Hydraulic Design of New WWBScour Analysis

19. Bridge Inspection Records Corps of Engineers records of work on the river Application of Corps of Engineers (Maynord) method for evaluation of bend scour Long term records available on the Internet Hydraulic Design of New WWBRiver Stability

20. Enhanced CCHE3-D Model with fully coupled sediment transport used to analyze main piers for various flow conditions Used to quantify shear stress in scour holes for SCRICOS & Stream Power/ Erodibility Index methods Hydraulic Design of New WWB 3-D simulation of tidal flow before old bridge demolished

21. Hydraulic Design of New WWB A select number of large scale tests were conducted at the USGS lab in Turners Falls ,MA

22. Hydraulic Design of New WWB Many small scale physical model tests were performed at FHWA’s TFHRC Lab

23. PIER DESIGN PROCESS

24. Q100 Scour: Dolphins Scour = 63 ft. at Dolphin; 55 ft. at pier

25. Q100 Scour: Fender RingScour =30 ft. at ring; 29 ft. at pier

26. Hydraulic Design of New WWBScour in Cohesive Materials Erosion rate tests were conducted using the EFA apparatus under development at Texas A&M University

27. Hydraulic Design of New WWBScour in Cohesive Soils Estimates of pier scour were provided by Dr. J. L. Briaud using the SRICOS method he has developed

28. Hydraulic Design of New WWB Scour in Cohesive Soils Estimates of scour depth were provided by Dr. George Annandale of Golder Associates, Colorado using Stream power/ Erodibility Index Method

29. HEC-RAS Maryland SHA (Neill ) Tidal Analysis 2-D Analysis 3-D Analysis Methodologies used in Hydraulic Analysis

30. HEC-18 Equations Wide pier scour equation Salim-Jones & Jones-Sheppard pier scour equations Sheppard pier scour equation Enhanced CCHE 3-D Model Hydraulic Laboratory Tests- large scale and small scale Erodibility Index Method - cohesive soils SRICOS Method - cohesive soils Methodologies used in Scour Analysis

31. The Scour Team Final recommended scour depths and pier geometry were determined by a team of hydraulic, structural and geotechnical engineers.

32. Any Questions?