I-35W Bridge Collapse - Week 48

Week 48 by Ivy Chang | September 28, 2010

Last pre-cast segment installed on northbound bridge

On July 5, construction crews installed the last of the 60 pre-cast segments on the northbound span of the new I-35W bridge. They joined the segments with steel rods, cables and pressure, which left a 7-foot gap that will be filled with two closure pours of cast-in-place concrete later this week. A hydraulic jack also was installed that pushes the two sides of the bridge farther apart until the final segment is cured. Then the jack will be deactivated, which exerts pressure against the last segment to hold all segments in place.

The segments directly over the river have ridges that fit together. Grout is pumped into the cable ducts of each girder to keep out water and prevent corrosion.

After installation, Flatiron-Manson erection superintendent Junior Salas crossed the remaining 7-foot gap on a metal

The ringer crane hoisted the final segment for the I-35W southound lanes on July 10. 2008

catwalk as more than 20 other workers, who helped join the last segments, watched the first person to walk across the new I-35W bridge.

On the southbound bridge, crews are installing the final segments that will go through the same process as the northbound bridge.

The Second Street Bridge is also constructed and waiting for rebar installation.

Grading, paving and pouring concrete increases

A Flatiron-Manson subcontractor painted the underside of the new bridge.

Construction activities during this week include:

  • pouring the concrete for Span 4 that connects Pier 4 to Abutment 5 on the north side of the river where epoxy-coated rebar has been placed on the northbound bridge,
  • removing the falsework (temporary support structures) under the approach span on the south side of the river,
  • highway paving, including medians, shoulders and ramps between University Avenue and Fourth Street Southeast,
  • installing light poles along the south I-35W roadbed from Washington Avenue and along the northbound entrance ramp from Washington Avenue to I-35W,
  • grading and other road work to prepare for paving the interstate from Washington Avenue to the abutment wall on the south end, and
  • removing sheet pile near the new retaining wall along the exit ramp from northbound I- 35W to University Avenue.

Traffic re-routed to accommodate truck deliveries

During paving, concrete trucks will use I-35W south of Washington Avenue and travel from the concrete plant through the project. Following paving, crews will cut expansion joints in the concrete once it has cured. Some streets and ramps, including University Avenue, will close in early evening during paving.

On July 14, Mn/DOT project manager Jon Chiglo will discuss the final steps to connecting the main spans of the bridge during a live interview on Twin Cities’ ABC network affiliate, KSTP-TV, at 6:10 a.m.