Signalized diamond interchanges are unique pairs of intersections characterized by interlocked left turns and relatively close spacing between ramps. A diamond interchange has four external entry points (origins) and four external exit points (destinations). To effectively operate a diamond interchange, it is critical to examine the external origin-destination paths and evaluate their impact on the interior storage and progression. This paper describes a series of performance measures derived from high-resolution signal controller data that can be used to 1) qualitatively and quantitatively assess the quality of progression of the interior movements; and 2) optimize the internal offset to improve traffic flows within the interchange. Additional performance measures for identifying internal and ramp queuing are also discussed. The paper concludes by recommending that the graphical performance measures be integrated into controller front panel displays and central systems to assist engineers in tuning and maintaining efficient operation of diamond interchanges.
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