I-35W Bridge Collapse - Week 35

Week 35 by Ivy Chang | September 28, 2010

The chair of the National Transportation Safety Board wrote a clarification letter to Bob McFarlin, acting commissioner of the Minnesota Department of Transportation, saying that the working relationship between the two agencies has proceeded with "full and complete cooperation of all the parties."

Mark Rosenker stated that a misunderstanding occurred when a document that detailed NTSB deliberations not to hold a public hearing referred to concerns about NTSB’s authority on the investigation into causes of the Interstate 35W bridge collapse. However, Minnesota elected officials read the documents and misunderstood the implications of having a public hearing, according to the letter.

Any public hearing that NTSB holds would usually require two to four months to arrange and does not involve public participation, Rosenker said. A public hearing that Minnesota conducts would be different from the NTSB, but the state has not decided if it will conduct a public hearing.

Superstructure work begins

Crews poured the first of the concrete for the Interstate 35W bridge superstructure, including forms for the sides and bottoms of the south approach spans, last week and this week. By the middle of April, crews will begin pouring concrete for the road beds of the same spans that stretch over land.

During the week of April 7, work on the structure included building forms and pouring cast-in-place retaining walls on the north side of the project, assembling the barge-mounted ringer crane that will lift pre-cast concrete segments of the main span into place, erecting falsework on both sides of the river, and installing the barrel for a pedestrian tunnel under the I-35W roadway on the south side of the river.

Concrete and road work proceeds seven days a week

The Minneapolis plant of Cemstone, the largest concrete supplier in Minnesota, is working evenings to provide concrete during the reconstruction. Bridge crews also are working night shifts seven days a week to complete the widening of the highway on the south side of the construction site, in the casting yard, and on the supports for the north approach.

As of April 8, 44 pre-cast segments for the main span have been cast, and crews plan to transport up to six segments each day to Bohemian Flats for storage. Some streets will close temporarily or will close during material hauling only.

Jon Chiglo, MnDOT project manager, continued to provide updates on the reconstruction quality control efforts with live coverage of the site on Twin Cities’ major television networks.