1. Eric Graves, P.E. City Traffic Engineer Alpharetta, Georgia
Adaptive Signal Control Technology:  Managing Risks, Achieving Objectives
Eric Graves, P.E.
City Traffic Engineer
Alpharetta, Georgia

2. Alpharetta Transportation System
50,00 Residents
Day Time Population~100,000
ADP HP
UPS
North Point LCI
Downtown LCI

3. 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

4. Traffic Operations 2 Public Works Crews 1 Signal Systems Engineer
Signs
Signals
1 Signal Systems Engineer
1 Traffic Engineering Technician
Inspect Construction Projects
Manage maintenance contracts
Striping
Loop Repairs

5. 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)

6. 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

7. 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

8. When Adaptive Makes Sense
Unpredictable Traffic Flow
High sustained growth
Freeway system interactions

9. When Adaptive Makes Sense
Agency Capabilities
Technician capabilities
Detection at 98%!!
Strong communications
Fiber along all major corridors
Stable Ethernet field network

10. When Adaptive Makes Sense
Agency Capabilities
Engineering Staff
In-house signal timing maintenance program
“One of the best signal timers in the state”

11. When Adaptive Makes Sense
Desire Continuously Optimized Timings!!

12. 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
Peak-hour performance on day 365 and 730 should be better than doing nothing
Pause for questions

13. 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

14. Identified Solutions SCATS – Cobb County SCOOT **OFFERED DEMO**
ACS Lite
InSync **OFFERED DEMO**

15. 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

16. Other Systems Considered
SCATS
New Firmware
New Detection
Separate Central System
OPAC
Distributed solution – more rigorous detection requirements
ACS Lite
Presently not available in TACTICS
Presently does not optimize cycle length

17. Next Steps SR 9 18 mile corridor
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

18. 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

19. SR 9 ATMS Project
GDOT/FHWA Required PM Team to follow Federal Regulations mandating System Engineering Process to select Adaptive Solution

20. 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

21. SR 9 ATMS Project
Project recently received NTP!!

22. egraves@alpharetta.ga.us eveith@alpharetta.ga.us
Questions??