Design Services Performed Under On-Call Agreement with the Iowa DOT
Snyder & Associates was tasked with planning and designing roadway shoulder repair work along an extensive stretch of Interstate 80 for the Iowa Department of Transportation (DOT). Spanning four counties (Jasper, Polk, Dallas, and Poweshiek) and over 117 total miles, the expansive project consisted of reconstructing mainline existing shoulders (inside and outside) and performing guardrail updates. Additionally, culvert extensions and various other drainage improvements were included in the project.
Unique Challenges Lead to “Virtual” Solutions
Several considerations had to be taken into account at the outset of this project. Foremost was the significant amount of traffic along the corridor which made performing a traditional field exam potentially dangerous. As many as 31,000 vehicles per day travel the project corridor and a significant portion of this traffic consists of large vehicles and semi-truck traffic.
To make this portion of the project as safe as possible, the innovative team members at Snyder & Associates conducted a preliminary “virtual field exam.” Prior to the field exam meeting, Snyder & Associates personnel visited the project corridor, taking detailed notes and photos of each area of concern. This information was then loaded into presentation software. This made it easy to hold the field exam meeting with all of the necessary stakeholders without the need for a large group visiting the actual site.
Poor Drainage & Expansion Considerations
Another consideration in the project corridor was the condition of the existing shoulder pavement. In many sections, it had deteriorated to a point where pavement replacement was the only solution. The shoulder pavement exhibited signs of frost heave during cold weather months and in several cases, it was severe enough to block drainage and allowed ice to build up at the edge of travel lanes during melt and re-freeze events. The shoulder replacement process in these areas also included the construction of a drainable base and installation of subdrain to correct this issue.
On the Polk County stretch of the project, future interstate expansion plans from four lanes to six lanes also needed to be taken into consideration. To account for this upgrade, the shoulders constructed between mileposts 144 and 152.5 were constructed to full-depth and full-width specifications to serve as the future lanes when the expansion occurs.
This substantial reconstruction project will provide a safe roadway network for years to come. Snyder & Associates is proud that the Iowa DOT continues to seek out our professional engineering and design services for their most complex projects.