Operational Effects of the Displaced Partial Cloverleaf Interchange

As the roadway infrastructure in the United States evolves, transportation agencies continue to seek effective interchange alternatives that can accommodate site-specific needs, such as high through and turning volumes, or optimized traffic signal operations (by minimizing the number of traffic signal phases). In recent years, innovative interchanges such as the diverging diamond have enabled transportation agencies to explore unique designs compatible with their specific needs. This paper introduces a new innovative interchange, known as a displaced partial cloverleaf (DPC) interchange. This unique interchange is characterized by a single intersection, six free-flow movements, only four movements controlled by the solitary traffic signal, an intersection location that can be shifted, and only 12 conflict points. The flexible intersection location can help an agency improve corridor progression, eliminate conflicting queues from nearby intersections, or enhance/maintain the bridge structure without compromising the intersection operations. A microsimulation study was conducted to compare the operational performance of a DPC interchange to that of a four-quadrant type B partial cloverleaf (PARCLO B-4Q) interchange, which is very similar in layout to a DPC interchange. Results show significant decreases in experienced travel time for left-turning vehicles with the DPC. The DPC interchange is recommended as an alternative option for interchanges with very heavy left-turning onramp demand in combination with heavy crossroad demand.