After presence detection, adaptive signal control, and transit signal priority were implemented on the Atlanta Smart Corridor total travel time decreased by 22 percent and total vehicle delay decreased by 40 percent across all peak periods.

Smart Corridor experience in Atlanta, Georgia

30 June 2010
US 41/Cobb Parkway/Northside Parkway,Atlanta,Georgia,United States

Summary Information

The Atlanta Smart Corridor project evaluated the implementation of SCATS (Sydney Coordinated Adaptive Traffic System) and Transit Signal Priority (TSP) as an integrated system designed to improve mobility, reduce emissions, and decrease the costs of delay and fuel consumption on an 8.2 mile section of US 41/Cobb Parkway/Northside Parkway located between the City of Marietta and Atlanta, Georgia. The project included three jurisdictions (City of Marietta, Cobb County, and City of Atlanta).

The project scope of work included the deployment of SCATS adaptive signal control hardware and software, TSP equipment, and presence detection (inductive loops and video detection cameras) at 18 intersections. In addition, new traffic signal controller cabinets, traffic signal heads, pedestrian signals, and pedestrian accommodations meeting ADA (Americans with Disabilities Act) standards were installed as needed.

Prior to the upgrade project, SCATS software was installed on a central server and made operational at the Cobb County TCC (Traffic Control Center). The City of Marietta and the City of Atlanta used regional computers to communicate with the Cobb County server and coordinate cross-jurisdictional control of adjacent traffic signals. TSP was enabled by modifying existing hardware and software used for emergency vehicle priority systems. In the City of Atlanta and Cobb County, additional upgrades were required at 15 intersections where two TSP detectors and a phase selector were installed at each intersection. All 60 CCT (Cobb Community Transit) buses were equipped with TSP emitters.


A before and after study was conducted to evaluate the effectiveness of both SCATS and TSP. For the SCATS study, travel time, delay, and stop statistics were recorded from probe vehicles traveling along the project corridor. The TSP study used riders to collect bus route timestamp and delay data at various bus stops and intersections on CCT Bus Route 10. Five (5) performance measures were evaluated, including: average travel time, standard deviation of average travel time, intersection stop rate, average intersection stop time, and on-time performance level of service.

Baseline data collection began in November 2009. After the system was implemented, tested, and accepted, post deployment data were collected in June 2010. Researchers examined normal peak period traffic flows (AM, Midday, and PM) in both directions of travel.


Travel time decreased after the implementation of SCATS on all sections in both directions. The largest overall improvement was in the AM peak, with a 29 percent reduction in travel time. The Noon and PM peaks saw an overall reduction of 17 percent and 21 percent, respectively. The total reduction in travel time across all peak periods was 22 percent.

Vehicle delay decreased after the implementation of SCATS on all sections in both directions. The largest overall improvement was in the AM peak, with a 54 percent reduction in vehicle delay. The Noon and PM peaks saw an overall reduction of 31 percent and 37 percent, respectively. The total reduction in vehicle delay across all peak periods was 40 percent.

As with travel time and delay, the southbound direction showed a greater reduction in vehicle stops than the northbound direction. The largest overall improvement was in the Noon peak, with a 42 percent reduction in vehicle stops. The AM and PM peaks saw an overall reduction of 33 percent and 28 percent, respectively. The total reduction in vehicle stops across all peak periods was 34 percent.

The addition of SCATS and TSP had minimal impacts on transit level of service (LOS), however, based on the data collected researchers indicated that the biggest LOS improvement would come from ensuring that the buses did not leave the scheduled stops ahead of their scheduled departure time.

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Atlanta Smart Corridor Project Evaluation Report

Author: TransCore

Published By: Georgia Regional Transportation Authority

Prepared by TransCore for the Georgia Regional Transportation Authority

Source Date: 30 June 2010


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Goal Areas


Related Metropolitan Integration Links

Link 16a: Transit Management to Arterial Management

Typical Deployment Locations

Metropolitan Areas


traffic signals, adaptive signals, bus priority, TSP

Benefit ID: 2011-00760