Several layers were examined as part of the highway improvement needs analysis conducted for the 2017 State Transportation Plan. Mobility and safety needs on the Primary Highway System were evaluated in order to target corridors where capacity needs were not identified, but corridor operation could be enhanced with improvements such as climbing/passing lanes, left- and right-turn lanes, acceleration lanes, wider paved shoulders, limited access, and geometric improvements. Improvements would be similar to a relaxed application of the Super-2 design concept. Over time, the targeted corridors would serve as a complimentary network to the state s multilane highway network. For more information, see iowadot.gov/iowainmotion.