I-35W Bridge Collapse
Design-Build Contract Awarded
On Oct. 8, 2007, the Minnesota Department of Transportation awarded a contract to the Flatiron Constructors, Inc./Manson Construction design-build of the new I-35 replacement bridge. The project is officially called the St. Anthony Falls Bridge Replacement Project. FIGG Bridge Engineers is the bridge design firm on the team. The theme for the bridge outlined in the team's proposal is Arches Water, Reflection. The new bridge will be a prestressed concrete segmental box girder bridge with two different curved pier options .
The prestressed concrete segments for the 504-foot center span can be cast offsite and transported to the bridge site for placement. The bridge will be constructed with high performance concrete to increase its durability. It will also be a "smart bridge" with embedded sensors and a comprehensive monitoring system. A full-day bridge design charette was held with input from the public, government groups, educational and cultural groups on the bridge pier option, the color, the bridge railing and other related items.
>> View the FIGG/Flatiron Power Point Presentation of the new bridge here (Minn. DOT Web site)
>> View the bridge schedule here (PDF file)
Minn. DOT Announces Replacement Bridge Costs
The Minnesota Department of Transportation has announced that the cost of the new I-35 W replacement bridge will be $393 million. That is $143 Million more than the $250 million that the Federal government promised to Minnesota. MN-DOT's Commissioner Carol Molnau gave the $393 million number at a meeting of the Minnesota Senate's Transportation Contingent Appropriation Group on Oct. 1 and also said "that number will probably rise" according to TwinCities.com.
>> Learn more about this meeting here
Minn. DOT Releases Extensive Photo Collection
The Minnesota Department of Transportation has released hundreds of photos of the bridge collapse and of the recovery efforts and debris removal efforts, including aerial shots.
>> View Aug. 2 ground photos here
>> Access hundreds of additional photos here
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Tim Davis/www.conphoto.net |
Details Released on Construction Repair Work Performed at the Time of the Collapse
The Minnesota Department of Transportation has released information about the construction repair work being performed on the bridge at the time of the collapse. The construction repair work was being performed by Progressive Contractors Inc. under a contract with Minn. DOT.
>> See the bridge repair plans here
Design-Build Contractor Selected
The Minnesota Department of Transportation selected a design-build contractor for its new I-35 W replacement bridge on Sept. 19, 2007. Minn. DOT announced that Flatiron Constructors Inc./Manson Construction were chosen based on a "best value" selection process. The Flatiron team's bid was for 437 total days and for a total cost of $233,763,000. The Flatiron team also scored highest on the technical proposal; their technical score was 91.47 while the second team's technical score was 67.88. Two of the three unsuccessful bidders have filed a formal protest with the State of Minnesota. This is now being investigated by the state of Minnesota. The Star Tribune is reporting that the difference may be related to the material chosen for the bridge -- that whether the bridge is a concrete bridge or a steel bridge may turn out to be a key issue.
>> Read an account of Minn. DOT's design-build selection here
>> View a PowerPoint presentation explaining Minn. DOT's bid selection process here
>> Read the Star Tribune story here
Road-User Cost Report Released
The Minnesota Department of Transportation's Office of Investment Management released a report entitled: "Road-User Cost Due to Unavailability of Interstate 35W Mississippi River Crossing at Minneapolis, Minnesota." The conclusion was that the road user cost was $400,000 per day due to the unavailability of the bridge. The calculations were based on 140,000 vehicles per day using the bridge.
>> Read the report here
Minn. DOT Offers First Look at Replacement Bridge Development
The Minnesota Department of Transportation issued a revised proposed layout and three typical sections for the new proposed I-35 W replacement bridge. The typical sections are cross-sectional views of what the bridge could look like with the new traffic and/or transit lanes. One view shows the proposed section if light rail transit is included, a second view shows the proposed section if bus rapid transit is included and the third view shows the proposed section if no rapid transit is on the bridge. Minn. DOT has provided the following details concerning the new replacement bridge:
- Scheduled to open in late 2008
- 100-year life span
- 10 lanes of traffic, five in each direction -- two lanes wider than the former bridge
- 180 feet wide to provide more lane and shoulder capacity -- the former bridge was 100 feet wide
- The project will use the design-build contracting method to accelerate construction.
- Minn. DOT will consider steel or concrete-and-steel construction.
- Minn. DOT is working on layout enhancements with the city of Minneapolis, the University of Minnesota and the BNSF Railroad.
- Minn. DOT is analyzing the feasibility of building the new bridge to accommodate a potential light rail line in the future.
- The federal government is providing $250 million for the new bridge without requiring the usual state funding match.
- There are federal requirements for using emergency relief funds.
- Improvements to interchanges on either end of the bridge are separate projects requiring separate funding.
>> View the revised proposed layout and three proposed sections here
Minn. DOT Technical Memorandum
The Minnesota Department of Transportation posted a technical memorandum from their Engineering Services Division dated July 19, 2007. This memorandum offers guidelines for in-depth inspection of fracture critical and other non-redundant bridges and for underwater inspections. The I-35 W bridge contained fracture-critical bridge members and the memorandum suggests, "Fracture Critical members must be inspected from an arms length distance every 24 months."
>> View the memorandum here
Structure Inventory Report
This report provides the condition codes (ratings) for the deck, superstructure (truss and bearings), and the substructure (pier, abutments, and footings/piles). If any of these receive a condition code of four or less, then the structure is classified as structurally deficient.
>> Read the report here
University of Minnesota Study
In 1990, the Minnesota Department of Transportation contracted with the University of Minnesota to evaluate the fatigue stresses within the I-35 W bridge's truss members. Field tests of the bridge were a part of their evaluations.
>> Read the University of Minnesota's report here
URS Corporation Truss Bridge Analysis
In 2003, the Minnesota Department of Transportation contracted with the URS Corporation to perform a more detailed fatigue and fracture analysis of the truss bridge and its truss members. The report from that analysis (listed as a draft report) and the Executive Summary provides recommendations and are available below for download.
In-Depth Bridge Inspection Reports
In June 2006, an inspection team completed an in-depth report for the Minnesota Department of Transportation on its inspection of the I-35W bridge over the Mississippi River in Minneapolis. The report includes images of the flaws, cracks and defects in the bridge found by the inspectors. Minn. DOT also prepared a detailed condition report on the bridge. It contains descriptions of the cracks found in certain areas of the bridge.
>> Read the full report with images here
>> Read the detailed condition report here
Detailed Bridge Information
Minn. DOT released a fact sheet on the I-35W Bridge including details and a short list of what work was being performed on the bridge at the time of the collapse.
>> View the information here