InSync adaptive traffic control system
The InSync adaptive traffic control system, developed by Rhythm Engineering, is an intelligent transportation system that enables traffic signals to adapt to actual traffic demand. As of March 2012, traffic agencies in 18 U.S. states have selected InSync for use at more than 650 intersections.
InSync is a plug-and-play system that works with existing traffic control cabinets and controllers. Its two main hardware components are IP video cameras and a processor, sometimes referred to as "the eyes" and "the brain" of the system, respectively. Mounted video cameras determine the number of vehicles present and how long the vehicles have been waiting (also known as delay). The processor, a state machine, resides in the traffic controller cabinet at the intersection. The system calls up the traffic signal state that best serves actual demand while coordinating its decision with other intersections.
Local Optimization InSync uses integrated digital sensors to know the exact number of cars demanding service at an intersection and how long they’ve been waiting. Approaches are given phasing priority based on this queue and delay data. InSync’s dynamic phasing and dynamic green splits enable the traffic signals to use green time efficiently.
Global Optimization InSync creates progression along an entire corridor by using “green tunnels.” Platoons of vehicles gather and are then released through the corridor. By communicating with each other, the signals anticipate the green tunnel’s arrival so vehicles pass through without slowing down or stopping. The green tunnels’ duration and frequency can vary to best support traffic conditions. Between green tunnels, the local optimization serves the side streets and left turns.
A survey of adaptive traffic control users published by HDR, Inc. in 2010 titled "Adaptive Traffic Control Systems in the United States: Updated Summary and Comparison" ranked the InSync system number one in a variety of measures, including affordability, up-time, maintenance, reduction in stops, reduction in delay and reduction in travel time.
Several speakers in the adaptive traffic control session at the ITS World Congress (Oct. 16-20, 2011, Orlando, FL) cited InSync's entry into the market as the cause of adaptive traffic control's rapid spread in the U.S. 2008–present.