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June 12, 2014 / Jim Fenton

A Visit to the County Traffic Operations Center

I recently attended a public meeting to discuss future plans for expressways in Santa Clara County. At that meeting, Dan Collen, the Deputy Director for Infrastructure Development, mentioned that they give tours of the County’s Traffic Operations Center (TOC), the place where they monitor the sensors and control the traffic lights on County expressways. I have always been curious about this, and jumped at the opportunity. After all, how many of us, as little kids, thought there were people who actually sat in those controller cabinets? (I did.)

The TOC is located in San Jose, near the Mercury News facility just off 880. Our tour was shared with a dozen or so officers from the California Highway Patrol. We began in a conference room with a short PowerPoint briefing describing the system. The system covers all Santa Clara County expressways except Capitol Expressway (where installation is still in progress, due to complete in 2016). The system includes:

  • Over 55 miles of 1-gigabit fiber optic network
  • Over 4000 in-road detector loops
  • 400+ high definition cameras
  • 100+ bicycle sensors
  • 25 pedestrian sensors
  • Battery backup providing several hours of operation in the event of a power failure.

 

Expressways congestion map (from http://congestion.countyroads.org)

Expressways congestion map (from http://congestion.countyroads.org)

The coordination system for the traffic lights is much more sophisticated than most of us realize. There are several programs for each of the lights, which kick in based on observed traffic patterns. They obviously have put a lot of effort into fine-tuning the signals to be as efficient as possible. If you think you understand the “rules” for any of these traffic lights, you probably have only scratched the surface. When you consider the amount of time and gasoline saved by expressway users, this system paid for itself in only 11 days. And there are substantial environmental benefits as well.

Most of the bicycle and pedestrian sensors are deployed on the streets crossing the expressways since the lights generally default to green along the expressway. When a bicycle is detected, the lights provide a somewhat longer crossing time than for other vehicles. The pedestrian sensors supplement the crosswalk pushbuttons: If they sense pedestrians taking longer than usual to cross the intersection, they will extend the light cycle to allow the pedestrian to finish crossing. This means that they can program the pedestrian timing for typical pedestrians, rather than needing to accommodate the slowest pedestrians, disabled people, and so forth.

PTZ camera at Foothill Expressway and Main Street, Los Altos

PTZ camera at Foothill Expressway and Main Street, Los Altos

Most of the cameras are in fixed positions viewing a particular direction of traffic on or crossing the expressway. These are supplemented in some locations by pan-tilt-zoom (PTZ) cameras that they can look around with, perhaps to see an accident that might be just out of range of the other cameras. The TOC does not record the video, apparently on direction from the County Council (somewhat to the disappointment of the Highway Patrol people touring with us). However, they are starting to provide video feeds to other jurisdictions, and that may in the future indirectly result in some recording capability. They also make near real-time video available to anyone on the Web.

After the briefing, we went next door into the control room itself. It looked like you might expect: lots of screens on the walls showing the status of various intersections. They also had satellite TV weather and news feeds to be able to anticipate and respond to external factors. They can view groups of cameras at any of the intersection, or get a large view of a single camera as needed.

Several aspects of this operation were quite impressive. A staff of four people operates this system, and these are the same people that maintain the physical facilities. So if somebody drives into one of the traffic signal controllers, it’s one of these same people that will go out and fix it. They also do electrical work at other County facilities, such as the private airports, as well. This is a very lean and efficient operation.

They also didn’t hire outside consultants for the integration of this system; the same staff built it from commercial components, using products from established traffic control vendors. As a result, they know the system inside and out.

Without a facility like this, traffic on our expressways would be substantially worse than it is, affecting quality of life and the ability for our economy to scale. The County Roads people, and all of us in Santa Clara County, have reason to be proud of our very state-of-the-art and efficient Traffic Operations Center.

Some interesting links:

 

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