Bridge project on budget, on schedule
Officials are pleased with the progress on the St. Croix River Crossing near Stillwater and expect the first contract involving the five foundation piers to be completed this fall.
David Solberg, the WisDOT Project Manager for the bridge, said the work progress is on budget and on schedule.
"The first contract for the five pier foundations totaled $37 million," Solberg said. "The second contract for the bridge itself will let Nov. 1. The anticipated start date is the winter of 2013."
He expects that bid to come in $250 to $350 million range. The cost of the entire project is estimated to up to $676 million.
"On the Minnesota side they have been very active with the approach work," Solberg said. "Everything east of Osgood Ave. should be completed this year. Next year they will complete the work between Osgood and Greeley Ave."
He said work on the bridge approach from the Wisconsin side is expected to begin next year. On the Wisconsin side, an interchange is planned just east of the Houlton Elementary School. Highway 35/64 from Somerset and New Richmond leads directly onto the new bridge. Highway 35 and County E will connect at the interchange east of the school.
Traffic going north from Hudson will actually travel over the new bridge traffic and connect at the interchange.
"We couldn't build the interchange right near the bluff of the river," Solberg said. "The bluff impacts would have been unacceptable and would have caused too many environmental concerns."
Next year the Wisconsin work will include the area from the bridge to County Road E; The following year from E to 150th Street.
He said the WisDOT real estate department is currently dealing with land owners on the highway right of way. All of the land near the river bluff has already been acquired.
The five piers that are currently being constructed will be upward of 400 feet tall, however, half that will be under the water -- the foundations that are currently under construction.
"If you looked at the entire pier it would be almost three-quarters as high as the King Plant smoke stack," he said. In reality, the columns above the water's surface were intentionally made to be low enough so they will not be visible from behind the bluffs on both sides of the river.
To build the five piers involves going deep into the limestone in 40 locations. The piers above the water will have a unique tapered design, with openings to give them a more natural look. The columns are also tapered to make them more visually pleasing.
"A straight column gives the illusion that it's wider at the top," Solberg said.
The new bridge will be what is called an extradosed bridge.
In an extradosed bridge, the deck is directly supported by resting on part of the tower, so that in close proximity to the tower the deck can act as a continuous beam. The cables from a lower tower intersect with the deck only further out, and at a lower angle, so that their tension acts more to compress the bridge deck horizontally than to support it vertically. The deck of an extradosed bridge can be thinner than that of a comparable span-beam bridge, but must be thicker than that of a conventional cable-stayed bridge of comparable span. The design is visually pleasing.
"This will be only the second extradosed bridge in the U.S." Solberg said. "The other is in Connecticut."
Another aspect of the new bridge will be a loop bicycle trail that will be about 4.7 miles. The loop will incorporate both the new river crossing and old Stillwater lift bridge. The loop will also connect to existing bike trails on both sides of the bridge and there is a plan to tie into a possible trail leading to Hudson and another to New Richmond. Organizers are currently exploring both possible routes.
The bridge itself will be nearly a mile long, with a state line plaque in the middle.
"Pedestrians will be able to have one foot in Minnesota and one in Wisconsin," Solberg said.
He said the current lift bridge carries about 18,000 cars per day.
"In the next five to 10 years we expect that to increase 25 to 30 percent. The future will depend on gas and the economy, but those numbers could grow even more if Somerset and Stillwater see a lot of growth." Because of the rural nature of Houlton he doesn't expect a tremendous amount of growth there.
"I know the bridge has been somewhat controversial, but when it's built I believe everyone will like it," Solberg said.