How Does Surtrac Work?

Real-time Control for Traffic Management

Surtrac is an intelligent traffic signal control system based on techniques from robotics and artificial intelligence. Surtrac treats the intersection control challenge in a whole new way - as a single machine scheduling problem. The technology is then able to schedule downstream neighbors to give visibility of future input jobs.

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Real-time Traffic Optimization & Communication

  1. The first thing Surtrac does, like any good robotic system, is it senses its surroundings, or what is going on, in real-time, at the intersection. It gets this information from a software integration/API with the existing sensing infrastructure which can include cameras, radar, or even induction loops.

  2. Surtrac processes this information and then, every second, via its patented scheduling software, creates an optimization plan for how to move multi-modal traffic through the intersection as efficiently as possible.

  3. Next, via a second software integration/API, Surtrac acts on this plan by sending commands to the controller to coordinate the signals in support of its optimization plan.

  4. Finally, Surtrac communicates information about its plan and the traffic that will flow from the intersection.

    • To neighboring intersections so that they can incorporate this information into their respective plans, which allows for both autonomy and coordinated control to happen naturally across the network as traffic conditions demand, as well as...

    • To connected vehicles, passengers, pedestrians, or any other connected device or system that might have use for this information.

System Behaviors

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Light Traffic
Focus on moving platoons without stopping, durations vary widely, very responsive
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Shoulder Periods
Shift toward queue management and more defined coordination
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Saturation
Queue management, less responsive to individual vehicles, heavy emphasis on dominant flows

Adapting in Urban Environments


Surtrac is designed specifically for urban road networks, where traffic is complex, dynamic, and multi-modal. Surtrac coordinates traffic in grid networks and corridors for the way people actually move around cities and towns.


  • Second-by-second optimization allows Surtrac to adapt quickly to unexpected congestion and/or reduced capacity

  • All adaptation is autonomous, as Surtrac optimizes based on current vehicle locations, not historical data

  • Surtrac handles lane closures, double parked vehicles, and other sources of uncertainty in real-time

  • Information about queues from downstream intersections (softpressure) allows Surtrac to avoid dumping vehicles into an already saturated link

  • Surtrac has been deployed extensively in networks with tightly spaced intersection with narrow roads

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