I-35W Bridge Construction

The busy Interstate I-35W bridge over the Mississippi River in downtown Minneapolis, Minnesota, collapsed at the peak of rush hour on Wednesday, August 1, 2007. Once the rescue operation was completed and the site was cleaned up, MN-DOT was anxious to get a new bridge built. The Flatiron company from Denver, Colorado, submitted the highest bid, and suggested a project plan that would take the longest. They did, however, score the highest on the technical review of the bid responses, and there was concern that the other bidders would not be able to meet their proposed timelines. As a result, Flatiron was selected to build the new bridge. They accepted what sounds like a nearly impossible project, to build a modern interstate highway bridge in a cramped urban location in the flight path to a major airport over a river that supported barge traffic, and do it within a year.

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These photos were taken on August 30, 2008. MN-DOT has stated that the bridge is now 98% complete. They further suggested that the bridge could be open within 30 to 45 days, and that they might announce an official opening date on September 2, 2008. The Republican National Convention is in town at the Excel Center from the 1st to the 4th, and the Republicans would really have liked to have seen the bridge open during the convention. That just wasn't quite possible, but an opening date around September 20 might be possible. There would still be clean-up work, landscaping, and details to finish, but at least some traffic lanes could be open by then.

Any questions about Flatiron's ability to deliver have long since been put to rest. While the site looked busy through the winter, there was little visible work done on the main span. Much of the work was in casting the segments and putting up falsework. Once Flatiron had all the pieces of the puzzle sorted out and the falsework in place, the bridge seemed to go up over the course of about 6 weeks in late May, June, and early July. Since then, most of the work has been in the details and finishing work.

Note that photographing this project has been difficult due to the one vantage point being the 10th Avenue Bridge, which limits photography to about a 30 minute window around 9:00 AM due to sun angles and shadows. In addition, a tall fence makes it impossible to see what you are shooting, so you have to simply hold up your camera, and see what you get. That has resulted in some shots that are a bit crooked, a bit off-center, or not framed as well as they might otherwise have been.

The photo above is a view of some of the landscaping work at the south end of the bridge. The photo below shows more landscaping work, plus one of the BGS (big green signs) that have already been erected. This sign points out the lanes that branch off for University Avenue and 4th Street.

The photo above shows a small work crew doing finish landscaping with the aid of a small skid-steer track loader. Note the Red Cross building in the background on the left, and the 3rd Avenue Bridge over the Mississippi River in the upper center of the photo. The photo below shows work being completed on the southern landing of the bridge. At this location, a cut stone retaining wall is used rather than an earthen fill to support the highway grade. Concrete guardrails and a tall center divider are being installed on this section of roadway.

The photo above shows how the the abutment ties into the first bridge span. The photo below is a better look at the first span of the bridge. The center divider and metal side railing is already competed on the main bridge span. The scissors life in the photo below are being used to provide access for workers to paint the bridge.

These two photos show the painting work on the main span. The photo below shows the entire main span, and the barges that are used to stage the work. The photo below is a close of the painting crews. The crews first grind or sandblast the concrete. They they apply two coats of plaster followed by a coat of acrylic Snowbound White paint. The paint colors were selected based on community input. The blue plastic is masking to prevent overspray from getting on the completed guardrails.

The photo above shows the completed piers at the north end of the main span. The decorative cradle at the top of the piers is complete and ready for paint. The University of Minnesota Tandem Physics Lab is visible just under the 3rd span on the right of the photo. That building narrowly missed being damaged when the original bridge collapsed. The photo below shows work underway on the smaller 4th bridge span.

The photo above is a close-up of the work being completed where the third and fourth span meet. The worker in the white bucket truck is grinding the concrete smooth where it will eventually be painted. The workers using the orange traveling scaffold and the orange lift appear to be installing light fixtures under the bridge. The photo below is a view of the north bridge abutment. The roadway is again supported by retaining walls surfaced with cut stone. Work is underway to finish the guardrails.

The photo above is a close-up view of work being done near the northern abutment of the bridge. Workers are installing a few remaining sections of the concrete deck, installing the joint at the very end of the bridge deck, and getting the center divider and guardrail ready for being poured using a slip-form concrete machine. The photo below shows that considerable activity is happening under the 4th bridge span. This is the location of a former railroad yard, and where the train cars were crushed when the original bridge collapsed.

The photo above is another view of the 4th bridge span with the Minneapolis city skyline in the background. I took this photo just because it was there. The photo below is the tunnel under 2nd Ave SE. This street was under the previous bridge. The new bridge is much shorter than the old bridge, so a tunnel was constructed for 2nd Ave SE. Workers are installing ceramic tile on the tunnel walls. Use of tile is standard in tunnels in Minnesota because it is much easier to clean than concrete.

The photo above shows the northern end of the ramps leading up to University Avenue. Note again that the big green signs are in place, as well as the smaller highway signs and traffic lights. The photo below is an overview of the construction project taken from the parking ramp at the Holiday Inn. This view is looking north, with the University frat row being on the far side of the river.

These two photos are views of the roadway at the south end of the bridge project. The casting yard was located here when the bridge segments were being manufactured. The pavement has either been repaired or replaced, and the roadway has been lowered as much as 20 feet. In the upper photo, the school bus is crossing on Washington Avenue heading west. The gas station in front of the HHH Metrodome is Bobby and Steve's Autoworld. The photo below has the University of Minnesota West Bank Office Building in the background. This building was originally built for classified military research projects such as the X-30 National Aerospace Plane, but is now used for accounting and purchasing, among other similar activities.