1 adaptive control software – lite (acs-lite) eddie curtis, p.e. fhwa resource center / hotm ntoc...

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Adaptive Control Software – Lite (ACS-Lite)

Eddie Curtis, P.E.

FHWA Resource Center / HOTM

NTOC Webcast

March 27, 2008

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Agenda

• Speaker Introductions

• Overview of traffic signal operations & Application of Adaptive Systems (Eddie Curtis)

– State of the Practice– Traditional methods – What does Adaptive control offer– Goals and Objectives of ACS-Lite (Federal Perspective)

• ACS-Lite (Steve Shelby)– System Development– System Architecture      – Functionality

• Tyler, Texas ACS-Lite Experience (Kirk Houser)– Description of deployment site– Objectives– Lessons Learned

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Speakers

Eddie Curtis, P.E.Traffic Management Specialist, FHWAOffice of Operation / Resource Center

eddie.curtis@fhwa.dot.gov

Steve Shelby, PhDResearch Projects ManagerSiemens Energy & Automation, Inc.Process Solutions Division (PSD)Business Unit Intelligent Transportation Systemssteve.shelby@siemens.com

Kirk Houser, P.E.City Traffic EngineerCity of Tyler, Texaskhouser@tylertexas.com

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Purpose of Traffic Signals

• Moving traffic in an orderly fashion;

• Minimizing delay to vehicles and pedestrians;

• Reducing crash-producing conflicts

• Maximizing the capacity of each intersection approach

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The State of Traffic Signal Operations

The Issues

D-D

C-

FC-

C

6 6

7

Which agencies are having the greatest difficulty

5351

65 67 65 67 6671

6669

30

35

40

45

50

55

60

65

70

75

Less Than < 50signals

50 to 150signals

150 to 450signals

450 to 1000signals

More Than1000 signals

Score by System Size

2005 Score 2007 Score

F

D D DC

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How is your signal system performing?

• There is no national standard of performance.

• Phone calls are frequently used as a measure;

• Before and After studies are relative measures;

• Reporting

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What could you do with Performance information?

• Proactively Manage

– Identify need for improvements

– Identify gaps

– Prioritize resources

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Traffic signals compete for resources

U.S. National Crash Characteristics

Crash Type Total Crashes Fatalities + Injuries

Number Percent Number Percent

Non-Intersection 3,599,000 57% 1,022,549 52%

Unsignalized Intersection

1,418,000 22% 481,994 25%

Signalized Intersections****

1,299,000 21% 462,766 23%

Total 6,316,000 100% 1,967,309 100%

Source: Adapted from Table 28 of Traffic Safety Facts 2002. (4)

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• Improve Safety

– Can improving signal operations enhance intersection safety.

– Do poor signal operations contribute to intersection crashes.

• Reduce Congestion

The connection between operations and safety

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Signal Timing measures that reduce crashes

• Provide progression– Time based coordination– Interconnect traffic signals– Centrally manage– Optimize offsets

• Optimization of signal timing– Retiming– Optimize phase splits

• Modify clearance intervals– Dilemma zone protection

• Provide Green Extension

• Advanced detection

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Recent activities

Improving Traffic Signal Operations

• 1975 Delay and Fuel consumption at traffic signals, Kenneth Courage,University of Florida,

(One Billion gallons of fuel)

• 1983 Traffic signal timing optimization, achieving national objectives through state and local

government actions, Gary Euler, FHWA

(Two Billion gallons of fuel, benefit/cost 63:1)

• 2004 The benefits of retiming traffic signals, Srinivasa Sunkari, TTI

» (MDDOT 215 INTS, 94% reduction in delay, 77% reduction in stops)» (San Jose 25 INTS, 35% reduction in delay, 39% reduction in stops)

• 2005 / 2007 NTOC Traffic Signal Report Card (D- / D) » (300 million vehicle hours of delay, major roadways, benefit/cost 40:1)

Traffic Signal Control Evolution

Late 1960sMid to Late

1980s Mid 1990s 2000

Open Loop SystemWith TrafficDetection

Closed Loop ControlCentral

Timing Plan selection byField Master

Closed LoopAdaptive Control

Timing Plan selection byField Master (ACS-Lite)

Centralized Control

UTCSCentral Control

Interval or Phase Control

Traffic Responsive /Adaptive Control

SCATSSCOOTATCS

Adaptive Control

RHODESOPAC

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Benefits of Adaptive Signal Timing

• Responsive to traffic conditions – Reduce traffic delay– Delays onset of saturated conditions

• Reduces or eliminates the need to retime traffic signals– $1800 – $3500 / intersection

• Improvements over Time Of Day plans– Travel time– Delay– Stops– Fuel consumption

• Data collection and archiving

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Signal Timing Design

0500

1000150020002500300035004000

12:00AM

2:00AM

4:00AM

6:00AM

8:00AM

10:00AM

12:00PM

2:00PM

4:00PM

6:00PM

8:00PM

10:00PM

Time of Day

VP

H (

veh

icle

s p

er h

ou

r)

Design Period

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The Signal Timing Process

• Trigger Event (Phone Call / Scheduled Retiming)

• Identify Intersection• Collect organize existing data• Conduct site survey• Obtain Turning Movement data• Calculate local timing parameters• Group signals• Calculate coordination parameters• Install and evaluate new plans

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Is the data were collecting significant?

Utilize peak 15 min day for 4 time periods

AM , Mid-Day, PM, Off-peak

15hr/day X 5day/wk X 52wk/yr X 3yr =

11,720 hrs

.0085 %

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Prolong the effectiveness of Signal Timing

0

5%

10%

15%

20%

25%

1 2 4 53

Time in YEARS

Prolongs the effectiveness of Signal Timing

Source: ITS Siemens

Adaptive

Adaptive Control Deployment

Currently Deployed Adaptive Systems

SYSTEM (# of Intersections)

SCATS 6 SCOOT 1 OPAC 2 RHODES 3 ATCS 4 Other 5 Total Intersections

TOTAL 906 193 62 41 756 472005

PERCENT OF MARKET SHARE 45.19% 9.63% 3.09% 2.04% 37.71% 2.34%

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Disadvantages

• High capital cost $$$

• Requires extensive calibration &

monitoring

• Requires active maintenance of

traffic detectors

• Communications overhead

• More technical staffing

• Oversaturated conditions

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Cost Performance

Proactive Management

Data

Typical Existing Systems

Cost

Performance

Proactive Management

Data

Typical Adaptive Systems

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FHWA Goals for ACS-Lite

• Low cost

• Leverage existing infrastructure• Retrofit with existing controllers• Fully actuated detector layout• Typical communications• Closed Loop systems

» 20,000 Systems

• Provide improvements over typical TOD timing

• Operate without connectivity to a TMC• Closed loop field master architecture

• Use NTCIP

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Benefits of ACS-Lite

Cost

Performance

Proactive Management

Data

ACS-Lite

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Private Sector Partners

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Integration Sites & Deployment

Gahanna, OH(Econolite)

Bradenton, FL(PEEK)

El Cajon, CA(McCain)

Houston, TX(EAGLE)

Tyler, TX November 07

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ACS-Lite Benefits

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Questions ????

Eddie Curtis, P.E.

Traffic Management Specialist

Phone: (404) 562-3920

eddie.curtis@fhwa.dot.gov