WisDOT to install sensors on deck truss bridges beginning Monday, October 22

October 18, 2007

Strain gauges will monitor traffic loads on 14 bridges similar in design to the Minnesota I-35 bridge that collapsed last August.

WisDOT to install sensors on deck truss bridges beginning Monday, October 22nd
Strain gauges will monitor traffic loads on 14 bridges similar in design to the Minnesota I-35 bridge that collapsed last August

As part of ongoing efforts to ensure the safety of transportation infrastructure, the Wisconsin Department of Transportation (WisDOT) will oversee installation of strain gauge sensors on 14 deck truss bridges in the state that are similar in design to the I-35 bridge in Minneapolis that collapsed August 1st. Installation of the strain gauges is scheduled to begin Monday, October 22nd and conclude on Friday, November 1st. The gauges will be left in place for three months to record round-the-clock data on the traffic load and resulting strain that the bridges accommodate.

"Public safety remains our top priority, and Governor Jim Doyle has asked our department to take this extra step to ensure that these bridges are adequately handling their daily traffic loads," said WisDOT Secretary Frank Busalacchi. "I want to thank all our partners including UW-Madison, UW-Milwaukee, and Marquette University for lending their support and engineering expertise to this bridge sensor project and our department's ongoing research efforts."

Immediately following the I-35 bridge collapse in Minnesota, all of Wisconsin's deck truss bridges were inspected and found to be safe. On a deck truss bridge, the superstructure typically consists of two parallel trusses that are the main load-carrying members of the bridge and the roadway is placed on top of the main members. Strain gauge sensors will be attached to each truss and then connected to a data collection unit.

"We fully expect to find that these bridges are functioning normally and safely," said WisDOT Structures Engineer Finn Hubbard. The state no longer builds deck truss bridges on the state system as they have been replaced with more modern designs. More information about Wisconsin bridges, the bridge inspection process and bridge sensors can be found on the WisDOT Web site.

The following chart details the location of Wisconsin's 14 deck truss bridges, the year they were built, and the scheduled date for installation of the bridge sensors. All bridge sensor installations are expected to begin at 8 a.m. dependent on weather conditions and equipment availability. Sensor installation on most of the bridges will require use of a specialized "Reach-all" vehicle.

EDITOR'S NOTE: Media interested in attending a bridge sensor installation should contact the appropriate WisDOT Regional Communications Manager: Mike Bie, WisDOT Southwest Region, (608) 246-7928 (for bridges in Crawford, Juneau, La Crosse, Monroe and Rock counties); Laurie Boettcher, WisDOT Northwest Region, (715) 833-9814 (for bridges in Dunn, Eau Claire, Polk, St. Croix and Trempealeau counties).

For more information, contact:
Finn Hubbard, WisDOT Structures Engineer
(608) 266-2375, finn.hubbard@dot.state.wi.us