Due to increased traffic use in the area, the interchange at I-70 and East Street in Junction City had become obsolete. East Street needed widening to accommodate traffic entering and exiting I-70, but the existing reinforced concrete box under the interstate would not allow for necessary structural changes. KDOT contracted BG Consultants to design a new interchange and two new bridges on the site.

The new bridges were required to span the widened roadway and increase the capacity of the bridge. Due to East Street’s alignment, BG had to design the bridges over it to be skewed 30 degrees right. In addition, the length required to span the roadway was greater than a conventional reinforced concrete haunched slab span bridge could handle, and the grade of the roadway was such that a deeper girder bridge would also be unfeasible.

BG’s solution was to design a post-tensioned reinforced concrete haunched slab bridge, which provides sections with less depth than a conventional structure. By post-tensioning the bridge both longitudinally and laterally, the concrete was tightly compressed to minimize hairline cracking in the deck. Fewer cracks mean less salt penetration into the concrete and therefore less corrosion of the reinforcing steel. Overall, these preventative measures and BG’s design will allow the structure to have a longer service life.