adaptive traffic signals - louisiana · for each detector channel during the last cycle. values are...

www.dotd.la.gov

Ben Boudreaux, PE, PTOE

Assistant Traffic Operations Engineer

District 07

Adaptive Traffic Signals

Adaptive Systems in District 07

1st Adaptive System (6 Signals)– I-10 EB & WB Exit Ramps in Westlake

– LA 378 Corridor

– Installed October 2017

2nd Adaptive System (7 Signals)– LA 108 Corridor in Sulphur

– Isolated Signals on US 90 & LA 27

– Installed July 2019

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What is an Adaptive Traffic Control Signal?

Real-time adaptive traffic control System

Adjusts signal timing based on current traffic– Establishes Cycle Lengths of entire corridor

– Adjust Split Times

– Adjust Offsets

Updates signal timings cycle by cycle

Long list of Manufacturers

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Parts of an Adaptive System

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Combustion Triangle

Ignition Source

Adaptive System

Adaptive Server

Parts of an Adaptive System

Detection– Magnetometers

– Video

– Loops

– Radar

– Others

Adaptive Server– Manufacturer Dependent

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Communication– Fiber

– Cellular

– Wireless

– Cup and String

Detection for Adaptive

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D2 D2

250’-500’

Back

Standard

Stopbar Detection

Advanced Detection

(Adaptive)

Adaptive Detection

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How Adaptive System Works

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Stopbar Detection

Adaptive Detection

Stopbar Detection

Adaptive Detection

Stopbar Detection

Adaptive Detection

Where Adaptive Systems Perform Well

Changing Traffic Patterns– Seasonal Traffic

– Large Trip Generators

– School

Random Traffic Changes– Detoured Traffic

– Temporary Lane Closures

– Sporadic Event

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Where Adaptive Systems Perform Well

Triggered Events – Emergency Evacuation

– User Defined Action

– Rapidly Clear Queue (Flush)

– Clear Sporting Venues

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Example Venue

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Advantages of an Adaptive System

Potential to Reduce Motorist Delay

Potential to Increase Capacity

Provide More Control/Options

Utilize Existing Infrastructure

Performance Measure Reports

Reduction of Crashes (2018 Study)

Reduce Emissions

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Disadvantages of an Adaptive System

Not Set and Forget

Requires Manpower to Properly Monitor &

Maintain.

Requires Operation of Additional

Components (Detection, Communication, &

Server).

Still Need Fallback Timing Plans

Additional Cost

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Westlake Adaptive System

In response to Sasol LNG Expansion

(installed by permit).

Utilize Magnetometer Detection (Primarily)

Utilize Video Communication for Stopbar

detection at 2 intersections.

Utilize Non-Licensed Radio and Cellular

Modems for communication.

Has a preemptive flush trigger for Interstate

Exit Ramps.

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Westlake Adaptive System

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Westlake Adaptive System

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Westlake Adaptive System

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Westlake Adaptive SystemObservations

Large Cycle Times

Long Splits on Mainline

Manageable Queues on Side Streets

Maintain Fair Progression

Most issues have been due to

magnetometers failures and communication

A few server issues.

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Westlake Adaptive SystemPerformance

Crashes– Intersection 1 (increased from 7 to 10)

– Intersection 2 (decreased from 13 to 11)

Travel Time– Slight Reduction

Complaints– Minor

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Westlake Adaptive SystemPerformance

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Westlake Adaptive SystemPerformance

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PRE

POST

LA 108 Adaptive System

In response to Axial Expansion, with some

signals funded by Sasol (installed by permit).

Utilize Radar for both Stopbar and Advanced

Detection.

Utilized wireless (Radio) for communication.

Alternative to Signal Retiming

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LA 108 Adaptive System

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LA 108 Adaptive System

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LA 108 Adaptive System

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LA 108 Adaptive SystemObservations & Performance

Cycle Times Slightly Larger during Peaks

No Reduction in Throughput Travel Time

Maintain Fair Progression

No Complaints

Need Additional Observation

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Travel Time Comparison

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Travel Time Comparison

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Communications of Adaptive Traffic Signals

Clarke Chauvin, PE, PTOEProject Engineer

Intelligent Transportation Systems, LLC.

Vehicle Detection Video Detection - Coaxial Radar Detection - Serial Magnetometer Detection - Wireless

IP Devices ATMS Controller Ethernet Switch CCTV Camera Bluetooth Detection

Local Communication

Cellular Modem Private Cellular Network

Used for isolated signal communications

Unlicensed Wireless Ethernet Radio 2.4 GHz range

5 GHz range

Used for signal corridor communications

Fiber Optic Cable Used to connect signal corridors to adaptive server

Backbone Communication

Wireless Radio

Cellular Modem

Rugged Ethernet Switch

Example Corridor Communications

Performance

Bluetooth Detection

Communications

PRTG

ATMS.now

System Monitoring

Adaptive User Interface

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Adaptive User Interface

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Adaptive User Interface (ATMS)

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Adaptive User Interface (ATMS)

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Ivica KlanacSystems EngineerCubic/Trafficware

Adaptive Management System

SYSTEM TOPOLOGY

• SynchroGreen Central Server

• SynchroGreen Local Intersections

• Detection

• Algorithm

CENTRAL SERVER/APPLICATION

• ATMS.now and SynchroGreen interaction– SynchroGreen is a SEPARATE application from ATMS.now

– ATMS.now can be used to change SynchroGreen settings and monitor commands

– ATMS.now is used to review historical data and troubleshoot events

– SynchroGreen can be on the same or separate server than ATMS.now

– Only ONE server can run SynchroGreen

OPTIMIZATION ALGORITHM

CYCLE / SPLIT OPTIMIZATION

CYCLE / SPLIT OPTIMIZATION

Target Phase Allocation =Green Utilization

Detector Calibration Factor (DCF)

With the same Green Utilization…A lower DCF results in a higher Target Phase allocationA higher DCF results in a lower Target Phase allocation

• Travel path optimization

• More volume, means more bandwidth

• Adjusts for queues

• Adjusts for trending early/late arrivals

OFFSET OPTIMIZATION

SYNCHROGREEN WEB INTERFACE

STATUS

Active/Inactive

Current datasheet

What intersection is running (Visible in ATMS)

>70% for SSM activation

Not Running Command

Pattern / Mismatch

Outside Tolerance

Not Coordinated

× Stale Command

× Cycle Zero Window

× Error calculating new plan/pattern

× Error optimizing to target cycle/greenband

STATUS

What is being sent to the controller

Green utilization for last phase

What controller wants to run based on demand and user constraints

Green Utilization / Next Split (estimate how much time next split is at saturation flow)

Green utilization error

M: Exceeds Max Utilization

D: NTCIP Detector Fault (e.g. Max Presensce)

INTERSECTION DATABASE

User input data that control how SynchroGreen calculates splits, patterns, and offsets at each intersection; and by extension, the entire group

INTERSECTION DATABASE - DEFINITIONS

Minimum/Maximum Cycle; Rate of Change

Minimum/Maximum Green Band

Minimum/Maximum Split; Rate of Change

Sets the Detector Calibration Factor

Stop bar detectors

Advanced detectors

Special Functions

INTERSECTION DATABASE – MINIMUM / MAXIMUM CALCULATIONS

• Minimum split and cycle length:• User defined minimum values

• SynchroGreen will not send calculate a split or cycle length that violates those values

• Quick notes:• SynchroGreen DOES check the Minimum Phase

values (MinGreen, Yellow, Red, Stop-in-walk, Shortway) and will use the higher between whats programmed and MinAllocation

• The ‘effective’ lowest cycle can be higher than the MinCycle if the sum of phases is greater than MinCycle

INTERSECTION DATABASE – GREEN UTILIZATION, ARRIVAL DETECTORS

• Used to measure Green Utilization on each phase

• Assign all the detectors on each phase

• Four Detectors max per phase• If more than 4 detectors on a phase, choose the

detectors with the highest green utilization

• Arrival Detectors are used to be measure counts on the advanced detectors and adjust relative offsets• If more than 2 detectors on a phase, choose the

detectors where traffic is not affected by turns. Typically, it’s the inside lanes

INTERSECTION DETECTOR STATUS

Lists the Occupancy (sec)and Volume measuredfor each detector channelduring the last cycle.

Values are smoothed.

Used for triggeractivation.

• Equipment Failure

Detector Fault

Communication Fault

• Traffic Conditions

Percent Utilization

Detector Occupancy

Detector Volume

TRIGGERS – TYPES AND APPLICATION

• Detector Fault

If detectors at this intersection fail, the System response will cause traffic conditions to be much worse than TOD

• Communications Fault

If communications at this particular intersection fail, continuing adaptive operations will cause traffic conditions much worse than TOD

If communications any intersection in this group fail, continuing adaptive operations will cause traffic conditions much than TOD

TRIGGERS – EQUIPMENT FAILURE

• Condition

Multiple Detector Failures

Detectors Fail on an Approach

TRIGGERS – DETECTOR FAULT

• Response

Shut off and run TOD

Change Intersection Pattern w/ Recalls

Change Intersection SG Database with different Min Allocations / Detector Calibration factors

• Condition

Lose communications to a specific controller

Lose communications to any signal in a group

TRIGGERS – COMM FAULT

• Response

Shut off and run TOD

ATMS.NOW & SYNCHROGREEN

• ATMS functions critical to SynchroGreen

• SynchroGreen Reports

• Purdue Reports

Summary

Adaptive Systems are not a Fix All

Adaptive Systems are not a set and forget.

Adaptive Systems require operating

detection, communication, & server.

Adaptive Systems can improve Travel Time

and Delay, as well as reduce Emissions.

Adaptive Systems can reduce crashes.

Adaptive is another tool to evaluate a

corridor’s performance.

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GO LSU

www.dotd.la.gov

Contact Information

Ben Boudreaux, PE, PTOE

337-437-9235

Benjamin.Boudreaux@la.gov

Ivica Klanac

Ivica.Klanac@cubic.com

Clarke Chauvin, PE, PTOE

clarke@itsanswers.com