Antony johnstone m_v2

RAC WA Signals Efficiency Presentation

National AITPM Conference

Adelaide, SA

14 August 2014

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The study looked at the Main Roads WA signal refinement processes to and examined to subject sites to determine/ identify the following:

• What signalised intersection treatments are currently utilised

• What signal improvements could be achieved

• Considerations and requirements for refining SCATS signal settings

• Signal refinement methodologies

• Performance measures and evaluation of signal timing performance

• Main Roads WA signal refinement policy, management, planning, and resources

Testing the use of an alternative method for optimising traffic signals, modelling with SCATS, to squeeze more from existing infrastructure.

Project Introduction

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Why do this study?

The dream:

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Why do this study?

The reality:

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What is SCATS?

Sydney Coordinated Adaptive Traffic System

• SCATS monitors traffic volumes in real-time and coordinates traffic signals.

• It adjusts the coordination and green time of signals depending on the traffic volumes detected on each approach.

• Approximately 900 signalised SCATS intersections in WA

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What is SCATS?

Image Courtesy of Google Street View.

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Qualitative Commentary• Information gathered from the Main Roads WA workshops and other

sources• High level overview of the SCATS signal settings

Quantitative Commentary• Micro-simulation models built with SCATS signal control• Several options tested• Morning, Midday, Evening, and Off peak periods modelled• On-site implementation and evaluation of AM and PM periods

Many subject sites were considered but two were selected for testing:• Orrong Road Corridor• Tonkin Highway/ Kelvin Road intersection

Project Methodology

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Tonkin Road/ Kelvin Road Site Description

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Option Testing Plan

Tonkin Road/ Kelvin Road Quantitative Analysis

Option Option Details

Option 1 Adjust SCATS signal settings including Master-isolated operation and optimal cycle time

Option 2 Test under a Double diamond overlap phasing

Option 3 Double right turn on Tonkin Highway north approach and localised additional lane flaring on the Tonkin Highway south approach

Option 4Ultimate test, adjustment of the SCATS signal settings including Master-isolated operation, optimal cycle time, and test under a Double diamond overlap phasing

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Percentage Change in Total Intersection Delay


AM Midday PM Off-Peak TotalOption 1 -5.4% -22.2% 5.7% -4.1% -2.5%Option 2 -10.8% -16.9% -5.8% -22.9% -9.6%Option 3 -57.9% -10.1% -13.0% -0.5% -35.5%Option 4 -34.3% -30.5% -16.2% -24.3% -26.8%

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Carbon Emissions (grams)


AM Midday PM Off-Peak TotalBase 6,986 4,597 8,949 1,397 21,927Option 1 7,638 4,570 9,793 1,362 23,362Option 2 7,644 4,593 9,752 1,270 23,259Option 3 6,559 4,229 8,552 1,321 20,662Option 4 7,796 4,290 8,653 1,264 22,003

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Orrong Road Site Description

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Orrong Road Model

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• Moderately high peak hour cycle times• Fixed split plan selection used in most cases• Link plans locked at times and not based on measured

flows

• Morning peak - Oats Street and Archer Street signals were the cause of westbound congestion

• Evening peak - Francisco Street signals were the cause of eastbound congestion

• Main road/ side road approach delays are not well balanced

Orrong Road Qualitative Analysis

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Option Testing Plan

Orrong Road Quantitative Analysis

Option Option Details

Option 1 Determine the optimal cycle time and refine SCATS data which will include operating incremental split selection

Option 2 Stagger the pedestrian crossing on Wright and Oat Streets

Option 3On the south approach of Francisco Place implement a left turn only with a u-turn bay on Orrong Road. At Archer Street and Wright Street implement a lag right turn. SCATS data refined.

Option 4 Testing of Oats Street under a double diamond overlap operation

Option 5 Ultimate test, as per Option 1 with further refinement to SCATS data and coordination

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Percentage Change in Total Corridor Delay


AM Midday PM Off-Peak TotalOption 1 -17.6% 25.8% 2.2% -7.0% -4.0%Option 2 -2.4% 0.3% -7.8% 2.1% -3.7%Option 3 -15.9% 2.4% 8.5% -7.8% -4.6%Option 4 15.5% 8.0% 33.3% -2.5% 20.0%Option 5 -16.8% 18.4% -13.2% -6.7% -10.0%

Equating this to annual delay cost to occupants, Option 5 would save approximately $760,000 per year in lost time cost.

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Carbon Emissions (grams)


AM Midday PM Off-Peak TotalBase 28,866 20,013 26,590 6,418 81,886Option 1 26,786 20,953 27,641 6,038 81,419Option 2 28,943 19,913 26,501 6,418 81,775Option 3 27,273 19,776 28,161 6,044 81,255Option 4 32,101 20,153 28,086 6,375 86,716Option 5 27,546 20,484 26,614 6,092 80,736

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0 500 1000 1500 2000 2500 3000 350000:0000:5901:5902:5903:5904:5905:5906:5907:5908:5909:59

Westbound Journey Times - AM Peak

BaseOption 1Option 2Option 3Option 4Option 5

Distance (m)

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01:59

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Westbound Journey Times - PM Peak


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0 500 1000 1500 2000 2500 3000 350000:00

00:59

01:59

02:59

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Eastbound Journey Times - AM Peak


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00:59

01:59

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Eastbound Journey Times - PM Peak


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• Option 5, widespread incremental split selection and optimal cycle time with refinement, has the largest improvement in terms of delay and average speed

• Option 1, 2, and 3 are considered to have performed slightly better than the base model overall

• While improvement can be found through changes to the SCATS signal settings, the current phasing setup can not be further improved.

Orrong Road Quantitative Analysis Summary

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Orrong Road Option 5 Implementation Results

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SCATS Signals Summary

Stage One Analysis summary:• Lower cycle times reduced the modelled delay• Widespread incremental split selection assisted in balancing

modelled delay on all approaches• Master-isolated as oppose to Flexi-link assisted modelled

performance

Stage One Broader summary:• Some intersections are already running close to their optimal

operation• The development of signal solutions should be done on a case by

case basis• Alternative signal auditing procedures, such as the one used for this

study, were part of the broader recommendations for the Main Roads WA Traffic Operations Centre (TOC).

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SCATS Signals Optimisation

It is not just the signals fault!

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Driver Inattention

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The WA Space-Time Continuum

Image Courtesy of Google Earth.

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Acknowledgements

RAC WA Policy and Research Team- Anne Still, Senior Manager- Una Mehta, Senior Traffic Engineer- Sarah Cutter, Senior Transport Planner

ATS – Bill Sissons

Main Roads WA TOC and Road Network Operations team

Aurecon – Steve Cotton, Peer Reviewer

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Thank You

Business

Antony johnstone m_v2