Willamette River Transit Bridge. Portland - Milwaukie Light Rail Willamette River Bridge WRBAC

Transcription

1 Portland - Milwaukie Light Rail Willamette River Bridge WRBAC

2 Vision Deliver a bridge that embodies the Portland aesthetic, is functional and affordable Aesthetic the right bridge for the context Function the right bridge for the use, site and environment Cost the right bridge for the budget Viable solutions must balance all three

3 Risks Fabrication Erection Material Superstructure Design Wave Frame Schedule 4 Pier Cable Stayed 2 Pier Cable Stayed

4 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed 4 Pier Cable Stayed

5 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed 4 Pier Cable Stayed

6 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed 4 Pier Cable Stayed

7 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed 4 Pier Cable Stayed

8 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed Team s Charge Develop methods to reduce risk profile of Wave Frame 4 Pier Cable Stayed

9 Risks Fabrication - Erection High performance steel at superstructure Option A: In place on temporary work platform Restrict navigation to month Wave Frame Helps manage construction risks Lowers labor cost Reduces schedule 2 Pier Cable Stayed 4 Pier Cable Stayed

10 Risks Fabrication - Erection High performance steel at superstructure Option B: Balanced cantilever method Higher construction risk Wave Frame Jones Act Increase labor cost 10% 2 Pier Cable Stayed 4 Pier Cable Stayed

11 Risks Fabrication - Erection Both Options Require High performance steel at superstructure Complex highly technical welding Wave Frame Higher cost and schedule risk One has HP steel superstructure 2 Pier Cable Stayed 4 Pier Cable Stayed

12 Wave Frame Construction Sequence - Revised

13 Wave Frame Construction Sequence - Revised Lifting of heavy prefabricated segments (400 ton)

14 Wave Frame Construction Sequence - Revised Advantages: Reduce construction cost less in-water work (Jones Act) Reduce on-site field welding Comparable construction schedule as Cable Stay bridge type

15 Risks Material - Superstructure High performance steel Available from only one source Volatile pricing Wave Frame Special run - availability limited Material sizes at upper limit of availability Higher cost and schedule risk One has HP steel superstructure 2 Pier Cable Stayed 4 Pier Cable Stayed

16 Wave Frame Use of High Performance Steel Revised Design: High Performance Steel only for top chord of wave Normal steel for remainder of bridge steel elements

17 Wave Frame Use of High Performance Steel Advantages: Excellent structural properties (high yield strength fracture toughness) Ease of welding

18 Wave Frame Use of High Performance Steel Disadvantages: Available from two sources Volatile pricing Special run limited availability

19 Risks Design Wave Frame Prototype design Complex steel to concrete connections Non redundant structure Wave Frame Higher cost and schedule risk 2 Pier Cable Stayed 4 Pier Cable Stayed

20 Wave Frame Structural Analysis Model

21 Wave Frame Structural Analysis Model

22 Wave Frame Structural Analysis Model

23 Wave Frame Structural Analysis Model

24 Wave Frame Complex Steel to Concrete Connection Initial Design Revised Design Concrete T section with shear stud connection Composite cross section with continuous I-Beam

25 Wave Frame Complex Steel to Concrete Connection Advantages: Simplification of pedestrian walkway construction Avoidance of shear studs (shrinkage creep concrete consolidation) Avoidance of post tensioning ducts Better strut to concrete beam connection

26 Wave Frame Redundancy of Bridge Elements Tension Members Initial Design: 4-inch thick plate Box configuration Revised Design: Thinner plates Double C configuration Top Chord Cross Section

27 Wave Frame Redundancy of Bridge Elements Tension Members Advantages: Top chord section with redundancy Elimination of 4 steel plates

28 Risk Summary Wave Frame High Performance Steel remains fundamental Lowered use of HPS Increased use of standard steel Simplified construction details and methods

29 Draft Risk Analysis Summary Wave Frame 2 Pier Cable Stayed Team s Charge Develop methods to reduce risk profile of Wave Frame 4 Pier Cable Stayed

30 Revised Risk Summary High Performance Steel remains fundamental to this bridge type Wave Frame 2 Pier Cable Stayed Risk profile lowered for wave frame 4 Pier Cable Stayed

31 Revised Risk Summary Questions? Wave Frame 2 Pier Cable Stayed 4 Pier Cable Stayed

32 Opportunities and Challenges

33 Evaluation Criteria Cost Risk Fundamental Performance Architectural Urban Context Greenway Environmental Sustainability Bridge Operations Miscellaneous Opportunities

34 Working Group Summary Wave Tied Thru Cable Cable frame Arch Arch Stayed Stayed Center-to-center Span Width Cost Risk Fundamental Performance Architectural Urban Context Greenway Environmental - Sustainability Bridge Operations Miscellaneous Opportunity To Be Determined Legend High Score Moderate Score Low Score Each alternative has opportunities and challenges

35 Opportunities and Challenges Cable Stayed 2 Pier

36 Cable Stayed 2 Pier Greenway Opportunity More open no landside piers

37 Cable Stayed 2 Pier Lifecycle cost Opportunity Low lifecycle cost - more concrete and less steel

38 Cable Stayed 2 Pier Navigation Opportunity 760 Clear Largest horizontal clearance

39 Cable Stayed 2 Pier Environmental Challenge 760 Clear Piers closest to shallow water

40 Cable Stayed 2 Pier Navigation Challenge Lowest vertical clearance (still exceeds 75 )

41 Cable Stayed 2 Pier Accommodation of curved spans at greenway Challenge Stay Cables Overhead Catenary Wire

42 Opportunities and Challenges Cable Stayed 4 Pier

43 Cable Stayed 4 Pier Lifecycle cost Opportunity Low lifecycle cost - more concrete and less steel

44 Cable Stayed 4 Pier Risk Profile Opportunity Lowest risk profile for schedule and budget

45 Cable Stayed 4 Pier Navigation Opportunity 700 Clear Second largest horizontal clearance

46 Cable Stayed 4 Pier Mode Flexibility Opportunity Accommodates various bike/ped train/bus configurations

47 Cable Stayed 4 Pier Greenway Challenge Landside pier closest to greenway

48 Cable Stayed 4 Pier Greenway Challenge Widest bridge over greenway 69 versus 66

49 Opportunities and Challenges Wave Frame

50 Wave Frame Innovative Opportunity Portland known for innovation: Light Rail Streetcar Tram

51 Wave Frame Environmental Opportunity 600 Clear Piers closer to deeper water

52 Wave Frame Environmental Opportunity 600 Clear Piers farther away from contaminated media

53 Wave Frame Navigation Challenge 600 Clear Narrowest horizontal clearance

54 Wave Frame Prototype Challenge Increase design and construction engineering costs

55 Wave Frame Prototype Challenge Increase design and construction engineering costs Bid risk Reduced competition for steel fabrication

56 Wave Frame Steel Challenge Higher price volatility than concrete

57 Wave Frame Steel Challenge Higher price volatility than concrete Increased lifecycle costs Weld inspections Impact to service for recoating (painting)

58 Wave Frame Contingency Hold Point Challenge FTA Hold contingency for high risk items Hold until high risk elements are 20% complete Funds held well into construction Opportunity to apply resources for other needs reduced

59 Opportunities and Challenges Questions?

60 Cost: Baseline Quantity Estimate Process Wave frame design was revised Construction methodology was revised Revised quantities were generated (all three) Design, market and construction risks were removed Result Baseline Quantity Estimate

61 Cost: Risk Assessment Process Wave Frame Risks and likelihood of occurrence were identified Impacts were assessed Mitigation strategies were developed Cost for mitigation estimated Result Cost range for design, market and construction risks

62 Cost: Risk Assessment Result Wave Frame Cost range for design, market and construction risks Potential Maximum Risk Value $16,900,000 Potential Minimum Risk Value $4,200,000 Recommended Risk Value $8,000,000 Result Conceptual Cost Estimate Ranges

63 Cost Estimate Difference between estimating what is shown today versus Contractor bid prior to contract award Design, Market and Construction Risk

64 Cost Estimate Cost to advance design from preliminary engineering to final design Plus Cost for construction engineering and inspection Wave Frame has a range Potential for higher design cost - prototype

65 Cost Estimate Unforeseen Conditions Change Orders

66 Cost Estimate National Constructors Group Estimates (NCG) Developed using labor costs, production rates, equipment costs, permanent and temporary material costs and contractor margin

67 Cost Estimate Difference between estimating what is shown today versus Contractor bid prior to contract award Design, Market and Construction Risk

68 Cost Estimate Cost for the Wave Frame established during Risk Workshop - $8,000,000

69 Cost Estimate Cost to advance design from preliminary engineering to final design Plus Cost for construction engineering and inspection

70 Cost Estimate Unforeseen Conditions Change Orders

71 Cost Estimate

72 Cost Estimate Greenway grading Address subsurface utilities Pier protection

73 Cost Estimate Cost range about $4M

74 Cost Estimate

75 Cost Estimate

76 Discussion

77 Next Steps WRBAC meeting for further deliberation of few viable types (January 13, 2009)??? WRBAC recommendation to Steering Committee (January 22, 2009)??? Additional design and process to refine vertical clearance (January to February 2009) Continued bridge design and refinement (Preliminary Engineering)

78 Thank you