Graphical Performance Measures for Practitioners to Triage Split Failure Trouble Calls

Abstract

Overview of Study LocationThe location used to demonstrate the use of the Abstract Graphical Performance Measures for Practitioners to Triage Split Failure Trouble CallsDetector occupancy is commonly used to measure traffic signal performance. Despite improvements in controller computational power, there have been relatively few innovations in occupancy-based performance measures or integration with other data. This paper introduces and demonstrates the use of graphical performance measures based on detector occupancy ratios to verify potential split failures and other signal timing shortcomings reported to practitioners by the public. The proposed performance measures combine detector occupancy during the green phase, detector occupancy during the first five seconds of the red phase, and phase termination cause (gap out or force off). These are summarized by time of day to indicate whether the phase is undersaturated, nearly saturated, or oversaturated. These graphical performance measures and related quantitative summaries provide a first-level screening and triaging tool for practitioners to assess user concerns regarding whether sufficient green times are being provided to avoid split failures. They can also provide outcome-based feedback to staff after making split adjustments to determine whether operation improved or worsened. The paper concludes by demonstrating how the information was used to make an operational decision to re-allocate green time that reduced the number of oversaturated cycles on minor movements from 304 to 222 during a Thursday 0900-1500 timing plan and from 240 to 180 during a Friday 0900-1500 timing plan.

Impact of Detector Configuration on Performance Measurement and Signal Operations

“…One limitation of GOR is that it tends to become saturated at relatively moderate levels of demand ( 10 ). Freije et al found that combining GOR with the occupancy rate of the first N seconds of red, which was called the red occupancy ratio (ROR), could be used to identify the occurrence of split failures ( 11 ). The researchers found that when both GOR and ROR were high, it was likely that a split failure occurred; a value of N = 5 s and 80% thresholds for GOR and ROR were found to work well in the initial study for identifying potential split failures.…”

“…In this paper, this is referred to as the first N seconds of red. Freije et al ( 11 ) suggested the use of N = 5.…”

Replicating Advanced Detection using Low Ping Frequency Probe Vehicle Trajectory Data to Optimize Signal Progression

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Sensor Fusion and MOE Development for Off-Line Traffic Analysis of Real Time Data

“…Attendees were asked to respond to the questions with the following scale: 5 Strongly Agree 4 Agree 3 Neutral 2 Disagree 1 Strongly Disagree Figure 4.3 shows the distribution of public sector and consultant attendees at the workshop. Thirty-nine participants returned the survey, and the majority self-identified as consultants.…”