FHWA Research and Technology Evaluation TechBrief: Innovative Intersection Design

Federal Highway Administration2021PDFBriefBadgley, JonathanFowler, JoshuaMahavier, KendallPeirce, SeanUnited States. Federal Highway Administration. Research and Technology EvaluationTurner-Fairbank Highway Research CenterHuie, MaryUnited States. Federal Highway Administration. Research and Technology EvaluationUnited StatesInterchanges and intersectionsRoundaboutsU turnsDiamond interchangesLeft turnsFHWA-HRT-21-101This brief summarizes an evaluation of the Federal Highway Administration\u2019s (FHWA\u2019s) Innovative Intersection Design (IID) program. FHWA\u2019s IID research and development (R&D) includes diverging diamond interchanges (DDIs), restricted crossing U-turns (RCUTs), displaced left turns (DLTs), median U-turns (MUTs), and mini-roundabouts. The purpose of the evaluation was to assess the effects of FHWA\u2019s investment in IID research on the availability and quality of such research, the adoption of IIDs in the United States, and the impact of those intersections on safety and operational performance.125