35W bridge rebuilding gets underway in earnest

By JIM FOTI, Star Tribune

Last update: December 18, 2007 - 12:58 AM

The new Interstate 35W bridge began to emerge on Monday with the pouring of a 200-foot-long slab of concrete that will help support 10 lanes of traffic just over a year from now.

The slab, 13½ feet wide and 4½ feet deep, won't be visible when the bridge is done, but it was on full display Monday as more than 40 cement trucks came by to make it happen.

Until now, much of the bridge construction has been below the surface, with crews drilling shafts 100 feet down and filling them with concrete. Those shafts will support footings similar to the one poured Monday.

Blue skies and temperatures in the 20s offered relatively pleasant December conditions for workers, but it still wasn't quite warm enough for the concrete. So the area being poured -- just above West River Parkway -- was draped in black plastic sheets, and diesel-powered heaters kept things from dipping below 40 degrees.

Instead of being dumped directly into the trench, the cement was pumped upward a few dozen feet through a hose that ran along a crane. The crane, which looked and moved like the arm of a giant desk lamp, allowed workers from Flatiron Constructors to put concrete where they wanted and made it easier to control the temperature.

The footing sits atop pilings driven deep into the soil and will take about a week to cure. The bridge's south abutment will be built atop it, while the area to the south will be filled in, with new approach roads going on top.

With the bridge completion date of Christmas Eve 2008 almost exactly a year away, Kevin Gutknecht, a spokesman for the Minnesota Department of Transportation, said that things were going well and that the deadline would be met.

Up the hill from where the footing was being poured, the main construction material has been neither concrete nor steel, but rather wood. The closed lanes of I-35W just south of Washington Avenue look like the back lot of a Menards, with wood and other materials stacked on the northbound half and workers' pickups parked in rows on the other side of the median.

The wood is being used to build the forms where the segments of the bridge's main spans will be cast in concrete. Four wooden casting beds are under construction on the freeway north of Washington. There will be a total of eight beds; on a project with more typical timetable, Gutknecht said, two to four beds would be used. Casting is expected to begin in mid-January.

For more scenes from the bridge work, visit www.startribune.com/roadguy.

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