Minnesota Department of Transportation
Design-Build Contract Awarded
On Oct. 8, MN-DOT 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-ft center span can be cast off-site 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 in the bridge and a comprehensive monitoring system. A full-day "Bridge Design Charette" will be held with the public, government groups, educational and cultural groups to decide on the bridge pier option, the color, the bridge railing and other bridge-related items. The Bridge Design Charette is currently scheduled to take place the week of Oct. 22.
View the FIGG/Flatiron Power Point Presentation of the new bridge.
MN-DOT Announces Replacement Bridge Costs
MN-DOT 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.
MN-DOT Releases Extensive Photo Collection
MN-DOT has released hundreds of photos of the bridge collapse and of the recovery efforts and debris removal efforts, including aerial shots.
Access hundreds of additional photos.
 |
Tim Davis/www.conphoto.net |
Details Released on Construction Repair Work Performed at the Time of the Collapse
MN-DOT has release 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 MN-DOT.
Design-Build Contractor Selected
MN-DOT selected a design-build contractor for its new I-35 W replacement bridge on Sept. 19. MN-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.
Click here to read an account of MN-DOT's design-build selection.
Click here to view a PowerPoint presentation explaining MN-DOT's bid selection process.
Click here to read the Star Tribune story.
Road-User Cost Report Released
MN-DOT's Office of Investment Management has 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.
To read the report, click here.
MN-DOT Offers First Look at Replacement Bridge Development
MN-DOT has 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. MN-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.
- MN-DOT will consider steel or concrete-and-steel construction.
- MN-DOT is working on layout enhancements with the city of Minneapolis, the University of Minnesota and the BNSF Railroad.
- MN-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.
To view the revised proposed layout and three proposed sections, click here.
MN-DOT Technical Memorandum
MN-DOT has posted a technical memorandum from their Engineering Services Division dated July 19. 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."
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 4 or less, then the structure is classified as Structurally Deficient.
University of Minnesota Study
In 1990, MN-DOT 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.
URS Corporation Truss Bridge Analysis
In 2003, MN-DOT 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 (MN-DOT) 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. The MN-DOT also prepared a detailed condition report on the bridge. It contains descriptions of the cracks found in certain areas of the bridge.
Click here to read the full report with images.
Click here to read the detailed condition report.
Detailed Bridge Information
MN-DOT has 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.
Click here to view the information.