EMTRAC Unveils Optical Signal Priority

Testing Long-Distance Optical Signals

March 27, 2013 – Traffic engineers from the Northern California region were able to watch demonstrations of the recently released EMTRAC optical Priority Detectors at the ITS trade show in Lodi, California on March 21st.

The Priority Detectors are installed in controller cabinets in place of phase selectors or signal processors (as they are called in optical-preemption applications). The Priority Detectors are able to receive signal-priority requests from all major brands of vehicle-mounted emitters, which flash pulsed frequencies of light toward pole-mounted detectors, which then forward the requests to the control cabinet.

At the trade show, EMTRAC Western Region Account Manager Luke Faubion, used third-party emitters (which are mounted on vehicles in the field) to show the EMTRAC system responding to optical priority requests—as well as RF requests sent by EMTRAC vehicle components.

“The ST-9365 Priority Detector is basically a universal phase selector because it can interpret signal requests from any of the optical brands out there, and that’s in addition to handling the 900 MHz requests that are sent from EMTRAC-equipped vehicles,” Faubion said after the show.

This dual functionality was a particular area of interest for a lot of the traffic engineers because 80 to 90 percent of agencies with the ability to request signal priority are still using optical systems and are unable upgrade to the more advanced EMTRAC RF/GPS-based system all at once.

“Agencies can begin upgrading some of their vehicles to EMTRAC while leaving the optical system in other vehicles. Their upgraded vehicles can then request priority earlier—and more reliably—and they don’t lose any functionality in the vehicles that still have optical equipment,” Faubion added.

Illustration of EMTRAC Optical-Request Signals
Optical/RF Priority Detector (top) 2 and 4-Channel Units (bottom)

In addition to the dual optical/RF Priority Detector, EMTRAC has also released two and four-channel optical-only Priority Detectors. As with the dual model, the optical-only units can easily be installed in directly into the input file of Type 170 control cabinets or may be provided with a Priority Detector Case for NEMA cabinets (when input-file space is not available). All optical units are capable of deciphering encoded signals.

Additionally, all units are provided with the EMTRAC Systems Manager software, which enables agency personnel to easily customize system settings, including:

  • Ranging Values: Define the acceptable signal intensities for specific intersection approaches
  • Output Connections: Modify controller outputs to accommodate non-standard connections
  • Vehicle Allow/Deny: Restrict signal priority for specified vehicles or request types

For specific information about how the EMTRAC system works with optical preemption systems, please refer to the following page:

EMTRAC Optical Equipment

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