AECOM developed the preliminary concept and final design for a three kilometre long reversible lane system for SR-173 (5400 South) in the Salt Lake City metro area of Utah. The goal of this project was to increase east/west mobility for western Salt Lake County. Reversible lanes were selected to reduce commute times and congestion on SR-173 without the need to construct additional lanes. The system can reverse three lanes of an existing seven lane urban arterial as needed to accommodate peak commute, special event, and emergency traffic. Unlike most reversible lane systems currently in operation, the uniqueness of the SR-173 system is that it can accommodate a two-way left turn lane which shifts with the reversing traffic lanes. This three kilometre long project required 18 signal structures (gantries) with changeable lane control signals placed over each lane. These gantries were placed and designed to allow for clear and safe transitions into and out of the reversible lane system. Within the system, gantries were placed and interconnected to work together as one system that includes coordination and communication with intersection traffic signals. Shifting left turns at signalized intersections from one lane to another creates unique safety and operational challenges. These challenges were addressed through innovative design and the application of state of the art traffic signal technology. Traffic signals employed dual function signal heads that can display either a ball or an arrow for the same lane. These signals were supplemented by changeable (blank out) signs to provide clear and positive direction to drivers. AECOM also defined a simple yet effective traffic signal operation plan to ensure that left turn lanes are safely cleared before transitioning the lane to opposing traffic. Because reversible lanes were new to both UDOT and the local driving public, the project required extensive stakeholder coordination and public outreach. AECOM worked closely with the UDOT TOC (the state-wide traffic management center), UDOT Region 2 Traffic and Safety Division, the City of Taylorsville, and other key stakeholders to meet operational, safety, and functional requirements. In-house experience with this type of project also allowed AECOM to anticipate and effectively address public comments and concerns.