St. Anthony Falls (35W) Bridge

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St. Anthony Falls (35W) Bridge
A computer generated image of the future St. Anthony Falls (35W) Bridge.
Official name	St. Anthony Falls (35W) Bridge
Carries	10 Lanes of I-35W and will be light-rail or bus-way-ready^[1]
Crosses	Mississippi River
Locale	Minneapolis, Minnesota, U.S.
Maintained by	Minnesota Department of Transportation (Mn/DOT)
ID number	NBI 27410 (Northbound), 27409 (Southbound)
Design	Concrete box girder^[2]
Longest span	504 feet (154 m)^[2]
Total length	1,216 feet (371 m)^[2]
Width	180 feet (55 m)^[1]
Height	120 feet (37 m)^[1])estimated
Clearance below	70 feet (21 m)^[2]
AADT	141,000 (2005 estimates)
Beginning date of construction	October 30, 2007^[3]
Opening date	December 24, 2008 (projected)
Coordinates	44°58′44″N, 93°14′42″W

The St. Anthony Falls (35W) Bridge^[4] will cross the Mississippi River in Minneapolis, Minnesota in the U.S., carrying north-south traffic on Interstate Highway 35W. It is being planned by Mn/DOT with input from Mayor R.T. Rybak and Governor Tim Pawlenty. The planning, design, and construction are to move faster than normal because the highway is a critical artery for commuters and truck freight.^[1]

1 Collapse of the previous bridge
2 Funding
3 Debate over the design
4 Final design
5 Project management
6 Construction
7 Effects on other projects
8 References
9 External links

[edit] Collapse of the previous bridge

The old, collapsed bridge

Main article: I-35W Mississippi River bridge

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, Minnesota collapsed, falling 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.^[5]

[edit] Funding

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

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

[edit] Debate over the design

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.^[11] Meetings between state transportation officials, Rybak, state transportation commissioner, Molnau, and 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."^[1] 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.^[12] State transportation commissioner Molnau, in conjunction with Metropolitan Council Chairman Peter Bell, recommended that light rail not be incorporated in the new bridge design.^[13]^[14] 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.^[15] Re-routing the Central Corridor light rail line to cross the river on the new bridge could save as much as $200 million in construction costs.^[16]

[edit] Final design

In the end, the St. Anthony Falls (35W) Bridge will be designed to carry five lanes of traffic in each direction on two separate roadbeds, eight feet apart. The total width will be 180 feet (55 m), 80 feet (24 m) wider than the I-35W Mississippi River bridge it replaces. Mn/DOT expects the bridge to be light-rail or bus-way-ready.^[1]

[edit] Project management

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. A typical bridge project of this scale in Minnesota would be expected to take 3 years to complete, but state transportation officials hope to open this replacement bridge in 15 months. 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.^[17] ^[18]^[1] Those bidders included:

KTM Constructors, (JV of Kiewit Corporation/Traylor Bros/Massman) - (New Tacoma Narrows)^[19] and (Benicia-Martinez Bridge)^[20] (Note: KTM subsequently withdrew their plans to bid on the project.)^[17]
Flatiron Constructors, Inc. and Johnson Bros. - (Escambia Bay Bridge)^[21] and (John James Audubon Bridge)^[22]
Walsh Construction/American Bridge - (Bay St. Louis, Mississippi bridge)^[23]^[24] and (Blennerhassett Island Bridge)^[25]
Ames Construction/Lunda Construction - (Crosstown Commons)^[26] and (Interstate 94 bridge over the St. Croix River)^[27]
C.S. McCrossan - (Hiawatha Light Rail)^[28]

Support posts being constructed on the north bank in January 2008

Piers take shape on north shore in May 2008

Box girder sections being formed in the casting yard in May 2008

On September 19, 2007 Mn/DOT announced that Flatiron Constructors and Manson Construction Company will build the bridge. The lead designer will be Figg Engineering.^[29] 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,^[9] the winning bid was for USD $234 million. Disincentives for missing the completion date of December 24, 2008 include a $200,000 per day penalty, while incentives to finish early can be as much as $27 million.^[30]^[31] Other projects by these companies include the Escambia Bay Bridge,^[32] John James Audubon Bridge,^[33] the Arthur Ravenel Jr. Bridge,^[34] and the San Francisco-Oakland Bay Bridge Skyway Phase.^[35] Figg Engineering was the lead designer on the Sunshine Skyway Bridge . ^[36]^[37]

[edit] Construction

MnDOT maintains a project page that tracks 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, a slab of concrete, 200 feet long, 13.5 feet wide, and 4.5 feet thick, was poured off-site, which will begin to shape the bridge. One hundred-foot deep pilings had already been sunken into the earth, which will support the ends of the bridge.^[38]. On April 8th, 2008 Mn/DOT announced it had reached the half way point of bridge construction, and may end up finishing the bridge ahead of schedule by as much as three months. ^[39]

There is significant speculation that the bridge will be completed before the December 24, 2008 promise date. The bridge construction is ahead of schedule and construction work is being performed in shifts: 400 workers during the day, and 200 at night.^[40]

[edit] Effects on other projects

Minnesota Department of Transportation's Lisa Freese, a deputy commissioner, has stated that the department expects some projects to be deferred or delayed as a result of the reconstruction efforts but that until exact costs and funding are determined they are unable to specify the exact effect on the rest of the state's highway program.^[41]