I-35W Bridge

My interest behind this bridge came from driving past it every night and seeing it lit up, it sparked my curiosity to do some research on the bridge. Using the new LED technology that is energy efficient, using 13% less than the traditional lamps that were previously used. These lights allow an even balance of light throughout the bridge, making it more comfortable for drivers, especially older ones. As for the underside of the bridge, consisting of blue, red, and green LED’s, creating different combinations, and they are working on making it light up for special occasions and holidays.

Twin Cities Pride Festival

Twin Cities Pride Festival

On August 1, 2007 the 35W bridge collapsed, resulting in the death of 13 people. This bridge was one of the ideas in the realization of the need for fracture-critical design, also the face of Dean Tom Fisher’s book.

35W Bridge Collapse

35W Bridge Collapse

September 18, 2008, only 11 months after the collapse, the bridge was rebuilt.This newly designed bridge is supposed to have over a 100 year life span that was also designed based off of a theme of “Arches – Water – Reflection” was chosen to express the design concept. Arches from the historic structure type seen along this stretch of the Mississippi River, Water for the significant crossing of the Mississippi River, and Reflection for both the literal reflection seen in the bridge forms and water surface of the river, and the spiritual reflection invoked by the history of the bridge site.

New 35W Bridge

New 35W Bridge

They also wanted to create a Corrosion Protection Plan to achieve the 100+ year life span by incorporating these key elements in this strategy:

  • Concrete bridge with post-tensioning in two directions, with 250 psi residual compression in the longitudinal top surface of the box girder.
  • High performance concrete containing silica fume and fly ash for low permeability.
  • Integral concrete wearing surface.
  • Post-tensioning durability system with polyethylene ducts, prepackaged thixotropic grout and multiple layer anchorage protection.
  • Structure health monitoring system, including deck corrosion potential sensors.1

I also realized that after the collapse of this bridge, they starting reconsidering all of the older bridges around the state, and checking their sustainability and reconstructing them if necessary. Unfortunately, it shouldn’t take a bridge collapsing and killing 13 people to make this realization, but at least it is finally getting done.

1 http://www.structuremag.org/article.aspx?articleID=892

http://www.johnweeks.com/i35w/i35w_night.html

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