Image source: ITD
Amidst a tight budget environment, Idaho Transportation Department (ITD) engineers stretched resources to perform a needed replacement of an old bridge in the small, eastern town of Mud Lake. The project review also will reduce traffic impact during the four-month-long project starting next fall after water leaves the canal.
Grading the roadway instead of installing guardrail will enable farmers to move large farm equipment across the new bridge, and will eliminate the sight-distance problems of the old bridge, which was built in 1954. The work will also allow the canal company to install a screen to catch wind-blown tumbleweeds and debris from the water's surface before they clog or damage intake pumps.
The state recently selected the Owsley Bridge project as an Excellence in Transportation award-winner for 2016.
Engineers first thought they’d need to replace the existing 120-ft-long Owsley Canal bridge, a three-span girder structure, on S.R. 33 with a similar structure, to the tune of $1.5 million. However, in studying water flow in the canal, engineers determined that an arch-pipe culvert structure could safely be used, at a savings of $700,000. Using multiple software applications and combinations, engineers employed 3-D and 4-D modeling to better analyze options. They found that a multi-plate pipe-arch culvert would do the job at far less cost.
ITD worked with the Mud Lake Water and Sewer Company and contractors to ensure that the 8-in.-diam. pressurized sewer line, which is bolted to the side of the old bridge, would continue functioning throughout the project. ITD also worked with the Owsley Canal Company to determine the type and size of the proposed replacement structure and to accommodate the canal company’s maintenance needs.