KL Engineering designed improvements to the STH 73 bridge over the North Fork Eau Claire River in Taylor County, WI.
Built in 1983, the existing deck had suffered through many northern winters and was starting to show its age. The advanced deterioration of the edge of the deck was a safety concern with crumbling concrete and rusting reinforcing steel.
This project was designed on an accelerated schedule, taking it from preliminary design to PS&E in just four months. The bridge deck was widened and replaced with a single span 36-inch prestressed girder bridge.
The new deck design included a closed parapet to meet current crash testing requirements, improved safety, and kept roadway runoff from corroding the edge of the deck. Additional structural improvements included extending the parapets and the use of asphaltic flumes to prevent erosion around the wing walls. Wing strapping was also added to prevent further tipping of the wing walls.
Viable detour routes for this portion of STH 73 were over 50 miles long. To reduce impacts on this long truck route, the bridge was redecked in stages. After careful analysis of the geometry of the structure, KL was able to maintain a single 12-foot lane on the structure during construction. A single lane of bi-directional traffic was controlled through the work zone by temporary signals.
The North Fork Eau Claire River bridge lies in the middle of an offset intersection with the west leg of Pine Drive just north of the bridge and the east leg of Pine Drive just south of the bridge. Vehicle sight lines were maintained by using minimum standards for bridge parapet heights and the guard rail was upgraded to current short radius standards. KL worked closely with WisDOT NW Region and Central Office in the detailing of a crash cushion to provide vehicular protection for the NW corner of the bridge where standard guard rail elements could not be used.