St. Anthony Falls (I-35W) Bridge

Transcription

1 St. Anthony Falls (I-35W) Bridge

2 Procurement Timeline August 1 Collapse Occurs August 4 Issue Request for Qualifications August 8 Short Listed Teams August 23 Request For Proposals Released September 14 Technical Proposals Received Technical Evaluation Begins September 18 Financial Proposals Received September 19 Project Letting September 20 City of Minneapolis Grants Municipal Consent October 8 Department of Administration Rejects Protest Project Award to Flatiron/Manson

3 Best Value Selection Process Based on cost plus time divided by technical score $200,000 per day for each day bid Formula: (Cost + (Time in days * $200,000))/Technical Score Resulted in Flatiron/Manson being awarded the best value contract technical score (out of 100 possible) $233.8 million cost 437 days to complete

4 Project Selection Results Proposer Technical Proposal Score Price Proposal 'A' Time (Days) Time (Days x $200,000) 'B' Adjusted Score (A+B) / Technical Score Low Score = Best Value Ames/Lunda $ 178,489, $ 78,400, ,588, C.S. McCrossan $ 176,938, $ 73,400, ,798, Walsh / American Br $ 219,000, $ 87,400, ,513, Flatiron / Manson $ 233,763, $ 87,400, ,511,129.33

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10 Bridge Geometry

11 Bridge Geometry

12 Bridge Alternatives Considered 1. Haunched plate girders/composite deck 2. Balanced cantilever cast in place construction from piers 2 and 3 3. Side spans cast in place on falsework, river span cast in place using travellers 4. All three spans cast in place on falsework 5. Side spans cast in place on falsework, main span boxes lifted as a single piece 6. Haunched Bulb T girders/composite deck

13 Precast Box Alternatives Considered 90 wide x 3 webs/box 90 wide 2 webs + struts

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16 Important Dates November 8 th : November 22 nd : November 26 th : November 30 th : December 3 rd : December 10 th : December 17 th : December 28 th : January 8 th : January 10 th : January 24 th : Test shaft RFC Actual load test Shaft layout RFC Bridge layout RFC Shafts 2NB, 2NB and 3SB RFC (2SB delayed) Pier 4 drilled shafts RFC Shafts 2SB RFC Footings 2NB, 2SB and 3SB RFC (3NB delayed due to tunnel lid and underfooting) Footing 4NB RFC Footing 4SB RFC Footing 3NB RFC

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18 Existing Road Railroad Track South Bank Mississippi River North Bank Historic Wall Phase 1 Existing Conditions

19 Note: Most of the photos have been omitted from this printed version.

20 Existing Road Railroad Track Historic Wall Poured November 15, 2007 Load test complete November 22, 2007 Phase 2 Drill Test Shaft

21 Existing Road Railroad Track Historic Wall All main bridge foundations completed February 2, 2008 Phase 3 Install Drilled Shafts and Pilings

22 Issues Pier 2 storm sewer was different size and location from earlier information Pier 2 existing footing wasn t in same location as expected; we drilled shafts in between existing shafts Pier 2 artesian condition made exploration work complicated Pier 2 SB unexpected low soil capacity required additional soil borings to decide if shaft diameter needed to increase to avoid artesian conditions

23 Issues Pier 3 storm sewer was different size and location from earlier information and required revising shaft layout and required increased shaft diameter Pier 3 NB tunnel access concerns required detached tunnel lid and scourable underfooting Pier 3 had conflicts with existing utilities

24 Issues Pier 4 had many unexpected utility conflicts, including the steam tunnel access for U of M and high voltage wires Pier 4 had low strength soils that weren t expected; no borings were possible pre-award due to debris; portion of pier 4 location was buried in 40 feet of sand at bid time Pier 4 borings weren t possible due to debris the first month of our project Pier 4 existing conditions required extensive rock removal to allow construction

25 Issues Artesian conditions were encountered in the test shaft, requiring drilling of second test shaft and late-in-the-game changes in the construction method Contaminated soils were encountered, complicating drilled shaft construction Removal of existing structure complicated early as-built condition surveys and exploratory drilling Design of typical shaft went from 70-foot depth up to 140 feet before test shaft; ended up around 85 feet depth after decision to go to double level loadcell to find skin friction capacity of two distinct different soil strata in borings; this variability made it hard to set up proper equipment and layout of work area

26 Phase 4 Cast Footings

27 Phase 5 Cast Piers and Abutments

28 Phase 6 Erect Temporary Supports