Adaptive Signal Control Technology: Managing Risks, Achieving Objectives Eric Graves, P.E. City...

Adaptive Signal Control Technology: Managing Risks, Achieving Objectives

Eric Graves, P.E.Eric Graves, P.E.City Traffic EngineerAlpharetta, Georgia

Alpharetta Transportation System

• 50,00 Residents• Day Time Population~100,000– ADP– HP– UPS– North Point LCI– Downtown LCI

Alpharetta Transportation System• 4 Interchanges with GA 400 (Limited Access Freeway)• 7, 4-6 Lane Arterial Streets• ~ 120 Traffic Signals– 3 Emergency Signals at Fire Stations– 1 Hawk Signal – April

• All newer equipment – GDOT ATC Program– 332 cabinets– 2070 controllers – SEPAC Firmware– Ethernet Communications

• 60% direct connections to City TCC

Traffic Operations

• 2 Public Works Crews– Signs– Signals

• 1 Signal Systems Engineer• 1 Traffic Engineering Technician– Inspect Construction Projects– Manage maintenance contracts• Striping• Loop Repairs

Traffic Operations

• Signal Systems Engineer– Signal Timing Maintenance Program– Systemic timing of all traffic signals every 2-3

years– Before/After travel time measurements – Timing reports to be published on the City Web

Site (soon)

Why Adaptive??

• Less $$ available for capacity improvements• Less opportunity for new roadway connections – Alpharetta is land locked and nearly built out

• Essential we operate our system as efficiently as possible– Initiative included

• Systems / Timing Engineer• PM Program• Timing Maintenance Program

Why Adaptive ??

• Traffic STILL a top concern from citizen survey• What else can be done???

• Cobb County SCATS System– Councilman read article on SCATS Success• Directed Staff to investigate options for Alpharetta

When Adaptive Makes Sense

• Unpredictable Traffic Flow– High sustained growth– Freeway system interactions

When Adaptive Makes Sense

• Agency Capabilities– Technician capabilities• Detection at 98%!!• Strong communications

– Fiber along all major corridors– Stable Ethernet field network

When Adaptive Makes Sense

• Agency Capabilities– Engineering Staff• In-house signal timing maintenance program• “One of the best signal timers in the state”

When Adaptive Makes Sense

• Desire Continuously Optimized Timings!!

Alpharetta Adaptive Signal Evaluation: Hypothesis

A well-timed system is a well-timed system

Cycle length- appropriate for volume Split percentages- balanced or prioritized Offsets- provide good progression

Alpharetta’s Criteria• Should be able to perform close to manual

optimized timings• Maximize the utilization of existing infrastructure– 332 cabinets/ 2070 controllers/ SEPAC Firmware– Ethernet Communications/ECOMM

• Optimize Progression on Corridors• Provide Queue Management• Coordinate crossing arterials??• Manual control??– Special events/Seasonal Peaks/Incidents

Identified Solutions

• SCATS – Cobb County• SCOOT **OFFERED DEMO**• ACS Lite• InSync **OFFERED DEMO**

Identified Solutions

• The City of Alpharetta performed demonstration projects with two adaptive platforms– InSync and SCOOT

• The results of the demo projects indicated that adaptive solutions could replicate current timing efforts– Potentially improving operations for special

events, unexpected events, and off peaks periods

Other Systems Considered• SCATS – New Firmware– New Detection– Separate Central System

• OPAC– New Firmware– Separate Central System– Distributed solution – more rigorous detection

requirements• ACS Lite– Presently not available in TACTICS– Presently does not optimize cycle length

Next Steps• SR 9– Sandy Springs– Roswell– Alpharetta– GDOT

• 18 mile corridor– Collector between outer suburbs and GA 400

interchanges– Primary arterial (Sandy Springs/Roswell)– Back up for GA 400

• PM Team identified Adaptive as an ITS Strategy

SR 9 ATMS Project

• PM Team initially considered performance Spec– FHWA/GDOT indicated that as written only one

vender likely fulfilled requirements– FHWA determined documentation was insufficient

to sole source

SR 9 ATMS Project

• GDOT/FHWA Required PM Team to follow Federal Regulations mandating System Engineering Process to select Adaptive Solution

SR 9 ATMS Project

• Systems Engineering Report completed and accepted by FHWA – Systems Engineering Process identified similar

functional requirements as the Alpharetta demo projects

– SCOOT determined as preferred option• Compatible hardware with jurisdiction platform• Ability to coordinate with non-adaptive intersections

using Tactics Central System

SR 9 ATMS Project

• Project recently received NTP!!

Questions??

egraves@alpharetta.ga.us

eveith@alpharetta.ga.us