Sequence Optimization at Signalized Diamond Interchanges Using High-Resolution Event-Based Data

Abstract

Signalized diamond interchanges are pairs of ramp intersections characterized by interlocked left turns and relatively close spacing. This paper describes a series of performance measures derived from high-resolution signal controller event data that can be used to optimize the internal phase sequence and offset to improve traffic flows within diamond interchanges and to assess the progression of the interior movements qualitatively and quantitatively. The new heuristic developed in this paper improves on traditional green band optimization techniques by incorporating actual demand profiles measured in the field. A field analysis was performed on a diamond interchange at I-69 and 96th Street in northwest Indianapolis, Indiana, where the existing sequence data were collected and used to model the alternative sequences to identify the optimal sequence. Interior operations were improved under the optimized settings: the percentage of vehicle arrivals on green increased by 19% during the 09:00-to-15:00 midday plan. Video observations were used to corroborate the data and are included in a video synthesis of the time–space trajectories.