June 18, 2018

Traffic Signal Performance Metric Discussion

Signal Performance Metrics Types

High Resolution Data/

ATSPMsVehicle Probe Data

Current Deployment Status

Background - Current Status

Hash - Goal

Solid - Achieved

https://www.tsbenchmarking.org/

Key Links

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https://www.fhwa.dot.gov/innovation/everydaycounts/edc_4/atspm.cfm

FHWA Everyday

Counts – 4

(2017 -2018)

http://www.pooledfund.org/Details/Study/487TPF-5(258) Traffic

Signal Systems and

Management

(2013 -2017)

http://www.pooledfund.org/Details/Study/629TPF-5(377) Enhanced

Traffic Signal

Performance

Measures

(2018 -2020)

http://docs.lib.purdue.edu/jtrpaffdocs/3/ http://docs.lib.purdue.edu/jtrpaffdocs/24

• Enhancements to Hi-Resolution Enumerations

• Development of New Performance Metrics

• Utilization of Probe Vehicle Performance Metrics

• Future Direction of DSRC and Performance Metrics

NCHRP 03-122 Performance-Based Management of Traffic Signals

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Focused on providing guidance to how traffic signal performance metrics could be beneficially incorporated into agency processes and, to the extent practical, the benefits and cost savings that result, such as:

• Organizational.• Planning• Design and Construction• Operations• Maintenance

• Completion 7/13/2018• Two Key documents

Performance-Based Management of Traffic Signals Guidebook

Performance Metric Data Dictionary

Identify Metrics to Answer the Following Questions?

What is the Cause of Congestion?

TRAFFIC SIGNALS

• Can we identify potentially unwarranted signals because volume dropped? (#204)

• How do arterials perform when impacted by other sources of congestion (incidents, work zones,

weather)? (#191)

• Is nighttime flashing operation better for reducing delay? (#196)

• What % of drivers travel from one end of a corridor to the other? (#189)

• What is wrong with existing signals? (#188)

• Are the controller inputs effective? (#190)

• How many intersections have undesirable phasing due to poor geometric design? (#197)

• How many vehicles arrive on green? (#185)

• How many split failures occur by phase? (#279)

• How much unnecessary delay is there with protected/prohibited left turns? (#195)

• How should signal timing be adjusted when other types of congestion occur? (#192)

• What phases are frequently skipped? (#205)

• What signals need to be retimed? (#187)

What Congestion Management Strategies?

• Are adaptive systems running optimal timings based on the corridor operational objectives? (#193)

• How does adaptive-predicted arrival on green compare with volume density or radar predicted arrival

detection? (#194)

• How does equipment perform? (#198)

• How many signals added per year? (#199)

• How many signals are modified per year? (#200)

• Is there a correlation between travel demand and the number of signals installed? (#201)

• What signals need to have broken equipment fixed? (#186)

• Are we seeing benefits from increased funding? (#209)

• How many signal unit staff are there per signal by district? (#206)

• How much time is invested on signal operational improvements by district? (#207)

• What is the ratio of time spent on operational improvements vs. reviews by district? (#208)

• Can predicted travel demand suggest desired performance of corridor? (#202)

Strategies to address traffic incident-related congestion:

Advanced Technology

Adaptive Signals

Retiming Program

Funding for Equipment Upgrades

Why do traffic signals cause congestion?

Unwarranted signals

Poor signal timing

Inadequate phasing

Timing doesn’t reflect current traffic volumes

Signal doesn’t respond to live vehicle demand

Equipment not functional

Improper controller programming

No communication between signals to maintain

synchronization

Program Goal:

Mitigate recurring

congestion

Discussion Questions

• How are states implementing Traffic Signal

Performance Metrics?

• What software platforms besides the open

source software are agencies utilizing?

• What other data sources are being utilized in

addition to the materials provided with ATSPMs

and probe vehicle metrics?

• Should AASHTO consider the adoption of

NCHRP 03-122 and enhance accordingly to

ensure industry consistency?

• Agency Examples that have lead to actionable

decisions?

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