01551102

Component

https://doi.org/10.3141/2487-03

Diverging diamond interchanges (DDIs) are an emerging interchange configuration that eliminates the need for left-turn phases in conventional diamonds and may be less expensive to construct than some alternative geometries. This paper examines signal timing for DDIs. DDI signal timing typically has used a two-phase configuration that reflects the two competing movements at the crossover points at each intersection of the DDI. This configuration inherently contains some inefficiency: (a) there is potential for internal queuing under two-phase configuration and (b) it is possible for the inflow demand to exceed outflow capacity of the interchange. This paper uses high-resolution event data to develop performance measures for evaluating operations at a DDI in Salt Lake City, Utah. Alternatives to the existing signal timing within the two-phase configuration are modeled and tested with a field deployment. The field deployment demonstrated the ability to prioritize ramp or through vehicles within the two-phase configuration. Additionally, a new three-phase configuration was developed and deployed to address the internal queuing that occurs with two-phase timing. With this new configuration, the flows from one DDI intersection to the other are balanced, and progression within the DDI is improved. With the implementation of the three-phase configuration, the percentage of vehicles arriving on green at the heaviest internal movement within the DDI increased from 53% to 92%. To illustrate these performance measures and improved DDI operation qualitatively, a video from a tethered unmanned aerial vehicle demonstrated the vehicle arrival characteristics by overlaying vehicle detection and signal state graphics on the video.

01580506

15-0645

English

pp 31–43

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369077

Print

Figures (9) ; Photos; References (18)

Diamond interchanges; Evaluation and assessment; Offsets (Traffic signal timing); Performance measurement; Traffic signal controllers; Traffic signal phases; Traffic signal timing; Video

Diverging diamond interchanges

Salt Lake City (Utah)

Data and Information Technology; Highways; Operations and Traffic Management; Safety and Human Factors; I73: Traffic Control

PRP, TRIS, TRB, ATRI

Dec 30 2014 12:19PM

• Bavarian Road Administration’s Use of Probe Data for Large-Scale Traffic Signal Evaluation Support
• Dynamic Turning Restriction Management for Signalized Road Network
• Emission-Based Signal Timing Optimization for Isolated Intersections
• Integrating Off-Ramp Spillback Control with a Decomposed Arterial Signal Optimization Model
• Performance Ranking of Arterial Corridors Using Travel Time and Travel Time Reliability Metrics
• Person-Based Adaptive Priority Signal Control with Connected-Vehicle Information
• Real-Time Estimation of Saturation Flow Rates for Dynamic Traffic Signal Control Using Connected-Vehicle Data
• Sequence Optimization at Signalized Diamond Interchanges Using High-Resolution Event-Based Data
• Use of Both Travel Time and Travel Time Reliability Measures to Quantify Benefits of Signal Timing Maintenance and Optimization