The area's native limestone and Dubuque's mining and industrial past inspire the designs for the bridge enhancements. Gateway arches announcing your arrival in Dubuque are featured at the bridges where  the Southwest Arterial (Future US Highway 52) crosses US Highway 151/61 and US Highway 20.  An important aspect of this project is to establish and coordinate a high level of roadway sustainable design thinking. In response, RDG developed the Southwest Arterial Sustainable Design Scorecard Handbook for use throughout the design and development of the corridor. The handbook incorporates the best, most applicable criteria and thinking from several industry standard sustainable systems.