The Zoo Interchange Core Phase II highway project was the largest single construction contract in the history of the Wisconsin Department of Transportation (WisDOT). The $310 million mega-project replaced all left-hand system ramps with right hand ramps, extended on and off ramp merge distances and made several safety improvements. The highway was expanded at several points along the route, including expansion from six to eight lanes along I-894/USH45.The project also required the construction of several bridges along the interchange, including 15 new precast girder bridges, two new plate girder bridges and four new tub girder bridges for system ramps.