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I-35W Saint Anthony Falls Bridge: Wikis


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I-35W.svg Saint Anthony Falls Bridge
Opening day, September 18, 2008, from south end.
Official name I-35W St. Anthony Falls Bridge[1]
Carries 10 Lanes of I-35W; light-rail or bus-way-ready[2]
Crosses Mississippi River
Locale Minneapolis, Minnesota, U.S.
Maintained by Minnesota Department of Transportation (Mn/DOT)
ID number NBI 27410 (Northbound), 27409 (Southbound)
Design Post-Tensioned Precast Concrete box girder[3]
Total length 1,216 feet (371 m)[3]
Width 180 feet (55 m)[2]
Height 120 feet (37 m)[2])estimated
Longest span 504 feet (154 m)[3]
Clearance below 70 feet (21 m)[3]
AADT 141,000 (2005 estimates)
Beginning date of construction October 30, 2007[1]
Opened September 18, 2008[4]
Coordinates 44°58′44″N 93°14′42″W / 44.97889°N 93.245°W / 44.97889; -93.245
I-35W Saint Anthony Falls Bridge is located in Minnesota

The I-35W Saint Anthony Falls Bridge crosses the Mississippi River in Minneapolis, Minnesota in the U.S., carrying north–south traffic on Interstate Highway 35W. It was planned by the Minnesota Department of Transportation (Mn/DOT). The planning, design, and construction were completed faster than normal because the highway is a critical artery for commuters and truck freight.[2] The bridge opened September 18, 2008, well ahead of the original goal of December 24.[5]


Collapse of the previous bridge

The previous 9340 Bridge, post-collapse

During the evening rush hour at 6:05 pm on August 1, 2007, the main spans of the I-35W Mississippi River bridge in Minneapolis collapsed and fell into the river and onto its banks. The collapsed bridge was built in 1967, was expected to carry 66,000 vehicles per day, and was expected to last fifty years. It was originally striped for two lanes in each direction. In 1988, in response to increased traffic demand, the four shoulders were converted to traffic lanes, accommodating four lanes in each direction. By 2004, an estimated 141,000 vehicles crossed the bridge each day.[6]


Minnesotans at a US DOT press conference. Left to right: Gov. Tim Pawlenty, Mayor R. T. Rybak, Secretary Mary Peters behind Rep. Keith Ellison (speaking), Rep. Betty McCollum and Sen. Norm Coleman.

Within hours of the previous bridge's demise, politicians pledged to rebuild the bridge at an accelerated pace. Federal transportation officials pledged US$5 million for the cleanup and recovery.[7] U.S. Representative Jim Oberstar, who represents Minnesota's 8th congressional district and chairs the House Transportation Committee, introduced an earmark[8] to direct a minimum of $250 million to help replace the bridge; the bill passed the House unanimously on August 3[9] as Republican Senator Norm Coleman and Democratic-Farmer-Labor (DFL) Senator Amy Klobuchar introduced companion legislation in the Senate.[10] President George W. Bush signed the legislation on August 6, 2007, after visiting the site on August 4.[11] After months of wrangling with Congress over spending proposals, President Bush signed the spending bill that included funding for the bridge on December 26, 2007.[12]

Design debate

Opening of bridge on September 18, 2008.

Minneapolis Mayor R. T. Rybak (DFL) said that future needs and policy considerations shouldn't be ignored in the rush to build a replacement and sought a new bridge able to handle increased traffic as well as mass transit.[13] Meetings between state transportation officials (Mn/DOT), Rybak, State Transportation Commissioner Carol Molnau, and Governor Tim Pawlenty yielded a desire to build a 10 lane bridge that will last 100 years, with the possibility of bus rapid transit or light rail lines. Rybak said, "Transit needs to play some role in this or otherwise we would need to build a much wider bridge in the future."[2] At a public forum in Roseville, hundreds of Twin Cities residents participated in a discussion about the bridge design. The overriding theme of the crowd was a desire to plan for the bridge's use of mass transit.[14] Commissioner Molnau, in conjunction with Metropolitan Council Chairman Peter Bell, recommended that light rail not be incorporated in the new bridge design.[15][16] But Pawlenty, responding to constituents and the mayor, directed Mn/DOT to design the bridge to be light rail-ready. He said the estimated additional $20 to $35 million would be paid for by the state.[17]

Award of contract

Bridge on September 20, 2008.

After the collapse of the bridge's predecessor, Mn/DOT announced to potential contractors that they should express their intention to bid on the project by August 8, 2007. A typical bridge project of this scale in Minnesota would be expected to take three years to complete, but state transportation officials hoped to open this replacement bridge in 15 months by using a design/build contract that allowed design and construction of the bridge to proceed concurrently. Mn/DOT announced on August 9 that five companies/consortia had been approved to bid on the project and requested that the bids be submitted by September 18, 2007.[2][18][19]

Despite criticism and a lawsuit that alleged that theirs was not the best proposal, Flatiron Constructors, Inc. and Manson Construction Company were awarded the contract on September 19, 2007; Flatiron's was the highest-priced and longest schedule of the bids submitted.[20] The lead designer was Figg Engineering,[21] with Ayres Associates providing hydraulic and scour analyses.[22] While the total cost was expected to be between USD $300 million and $350 million for the 1,900-foot (579 m) multi-span bridge, including financial incentives for accelerating the schedule,[11] the winning bid was for USD $234 million. Disincentives for missing the completion date of December 24, 2008 included a $200,000 per day penalty, while incentives to finish early could have been as much as $27 million.[20][23]


Piers take shape on north shore in May 2008

MnDOT maintained a project page that tracked all activities associated with the construction of the bridge including weekly updates, traffic impacts, construction photos, animations, and virtual walk tours. On December 17, 2007, the first slab of concrete, 200 feet (61 m) long, 13.5 feet (4.1 m) wide, and 4.5 feet (1.4 m) thick, was poured off-site, which began to shape the bridge. Pilings sunk 100 feet (30.5 m) into the earth support the ends of the bridge,[24] which contains 50,000 cubic yards (38,000 m3) of concrete.[25]

The bridge construction progressed more quickly than expected. Construction work was performed in shifts with as many as 400 workers during the day, and 200 at night.[26] On April 8, 2008 Mn/DOT announced the half way point of construction had been reached, and predicted that completion might be ahead of schedule by as much as three months.[27]

This prediction was borne out by events, as the Minnesota Department of Transportation opened the bridge to traffic at 5:00 in the morning on September 18, 2008.[4] Minnesota State Patrol cars at both the north and south ends allowed rush hour traffic to build up behind them. Once the construction barricades were removed at 5:00 am the First Responders, State Troopers, and Mn/DOT trucks slowly crossed the bridge with rush hour traffic in tow, officially opening the bridge. Flatiron-Manson is expected to earn $27 million in bonuses for accelerated performance.[28]


The bridge is equipped with anti-icing sprayers and was constructed with high-strength concrete. Three hundred and twenty three sensors regularly measure bridge conditions such as deck movement, stress, and temperature. The data will be compiled and analyzed by University of Minnesota personnel. The bridge is illuminated with light-emitting diodes.[29] Although LED lighting is not generally approved for such highways, this bridge roadway illumination is a test project.[30][31] The bridge also incorporates multichromatic decorative lighting, which is used to illuminate the structure at night.


The bridge has been named a project of the year by the American Public Works Association.[32] The association awards are presented annually to recognize excellence in public works projects.

The bridge is a finalist in the 2009 America's Transportation Awards for "representing the best in innovative management, accountability and timeliness".[33][34]


  1. ^ a b "I-35 St. Anthony Falls Bridge". Minnesota Department of Transportation. Retrieved 2009-03-11. 
  2. ^ a b c d e f Scheck, Tom (2007-08-07). "Rebuild may begin in September". Minnesota Public Radio. Retrieved 2007-08-08. 
  3. ^ a b c d Hoppin, Jason (2007-10-09). "The design for the I-35W replacement bridge is unveiled". Pioneer Press. Retrieved 2007-10-09. 
  4. ^ a b "Engineer: Mn/DOT to open I-35W St. Anthony Falls Bridge to traffic at 5 a.m. Thursday, Sept. 18". MnDot. 2008-09-15. 
  5. ^ "Drivers, Businesses Celebrate 35W Bridge Reopening". WCCO. 2008-09-18. Archived from the original on 2008-11-08. Retrieved 2008-09-18. 
  6. ^ Stachura, Sea (2007-08-06). "Too much stress on I-35W bridge?". Minnesota Public Radio. Retrieved 2007-08-07. 
  7. ^ At Bridge Site, Search of River Moves Slowly, By Monica Davey, New York Times, August 3, 2007
  8. ^ Jenks, Paul (2007-09-27). "CongressLine by The Earmark Reality". LLRX. Retrieved 2008-09-29. 
  9. ^ "House Panel Approves $250M Fund Request For Bridge". WCCO. 2007-08-02. Retrieved 2007-08-07. 
  10. ^ "House panel approves bill to provide $250 million for bridge". 2007-08-02. Retrieved 2007-08-02. 
  11. ^ a b "Minnesota sets ambitious goal for bridge fix". MSNBC. 2007-08-06. Retrieved 2007-08-07. 
  12. ^ Gardner, Amy (2007-12-27). "Bush Signs Domestic Spending Bill but Criticizes Pet Projects". Washington Post. Retrieved 2007-12-28. 
  13. ^ Scheck, Tom (2007-08-05). "I-35W bridge reconstruction could delay other projects". Minnesota Public Radio. Retrieved 2007-08-07. 
  14. ^ Mador, Jessica (2007-08-16). "Residents have plenty to say about bridge replacement". Minnesota Public Radio. Retrieved 2007-08-24. 
  15. ^ Lohn, Martiga (2007-08-11). "Dive resumes at bridge site after delay for fast-running river". Minnesota Public Radio. Retrieved 2007-08-12. 
  16. ^ "Letter from MnDOT Commissioner Carol Molnau and Metropolitan Council Chair Peter Bell to Governor Tim Pawlenty" (PDF). MnDOT. 2007-08-10. Retrieved 2007-08-12.  (letter from Molnau and Bell to Governor Pawlenty recommending LRT not be included).
  17. ^ Foti, Jim (2007). "State's plans for new I-35W bridge include light rail". Star Tribune. MSNBC. Retrieved 2007-08-24. 
  18. ^ "Contractor drops bid to build replacement I-35 bridge". Minnesota Public Radio. 2007-08-28. Retrieved 2007-08-28. 
  19. ^ Scheck, Tom (2007-08-09). "MnDOT chooses five finalists for 35W rebuild". Minnesota Public Radio. Retrieved 2007-08-10. 
  20. ^ a b Martiga Lohn, Martiga Lohn (2007-09-19). "Rich contract awarded for I-35W bridge replacement". Minnesota Public Radio. Retrieved 2007-09-19. 
  21. ^ "I-35W Contract Awarded, Conceptual Design Unveiled". Architectural Record, Mc-Graw Hill Construction. 2007. Retrieved 2007-11-12. 
  22. ^ — Colorado Engineering Awards
  23. ^ Scheck, Tom (2007-08-24). "State offers bonus for quick bridge replacement". Minnesota Public Radio. Retrieved 2007-08-24. 
  24. ^ Foti, Jim (2007-12-18). "35W bridge rebuilding gets underway in earnest". Star Tribune. Retrieved 2007-12-28. 
  25. ^ Fountain, Henry (March 30, 2009). "Concrete Is Remixed With Environment in Mind". The New York Times. Retrieved 2009-03-30. 
  26. ^ — Reality Check: Speedy Road Construction
  27. ^ - Bridge milestone, halfway done
  28. ^ "Collapsed bridge may be rebuilt by September". MSNBC. 2008-06-18. Retrieved 2008-08-14. 
  29. ^ Mador, Jessica (2009-09-16). "Cutting-edge technology makes new 35W bridge a model for future". Minnesota Public Radio. Retrieved 2009-09-16. 
  30. ^ Foti, Jim (2009-10-19). "Low-tech freeway light replacements, courtesy stimulus funds". Star Tribune. Retrieved 2009-10-26. 
  31. ^ Kinzey, B.R.; Myer (M.A.). "Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting (PNNL- 18687)". Richland, Washington: Pacific Northwest National Laboratory. Retrieved 2009-10-26. 
  32. ^ 35W Bridge Named Project of the Year
  33. ^ Vote for America's Best Transportation Project
  34. ^ Smart Bridge Technology: Minnesota Department of Transportation I-35W Minneapolis Bridge Replacement Project

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