EMTRAC Wayside Equipment

Priority Detector

The EMTRAC Priority Detector enables secure vehicle-to-intersection (V2I) communication by utilizing a 900-MHz spread-spectrum transceiver and a single-board computer integrated in a dual-card assembly that plugs into the traffic cabinet’s detector rack or on an interior shelf. Priority Detectors are also capable of communication using NTCIP protocols.

The Priority Detector is compatible with NEMA, 170/2070, Caltrans, ITS, and custom cabinets. It support up to 16 inputs, allowing for priority calls to be received for multiple phases from EMTRAC Vehicle Computer Units.

The EMTRAC Omni-Directional Antennas provide 2.15 dBi gain performance. The antennas are ground-plane independent and can be mounted in a variety of locations. Antenna wiring is encapsulated to provide exceptional resistance to extreme weather conditions.

Rack-Mount Priority Detector in Traffic Cabinet
  • Includes serial RS-232 or Ethernet communications to enable remote monitoring of system activity and configuration of EMTRAC equipment through the existing traffic network
  • Supports up to 16 inputs and 16 outputs, with one auxiliary output configurable as a satellite timing signal
  • Logs up to 5,000 locally-stored events (up to 10,000 events with removable memory)
  • Four main directional outputs and up to 12 auxiliary outputs are provided, with each input and output signal optically isolated for 2,500 volts
  • Operates on 120 VAC with its own power supply, and fits NEMA, 170/2070, ITS, Caltrans, and custom cabinets
  • Includes indicator lights for power on, signal received, active-output by priority, and direction of signal or channel
  • Includes toggle switches to send output in either Priority 1 or Priority 2 mode, allowing manual testing of detector function and intersection response. The Standby/Active switch enables testing and configuration without affecting the live signal
  • Compatible with all major brands of NEMA and 170/2070 controllers

Vehicle Interrogator

The EMTRAC Interrogator System enables agencies to automatically transfer activity logs from EMTRAC-equipped vehicles and to upload firmware and database updates to these same onboard units.

As equipped vehicles return to the garage or station, the Vehicle Interrogator utilizes secure wireless communication to download activity logs from onboard EMTRAC units. This data is forwarded to the EMTRAC server, where it can be viewed by agency personnel.

The EMTRAC Vehicle Interrogator may be installed at bus garages, fire stations, rail operation Centers, municipal-vehicle garages and lots, as well as maintenance facilities.

Photo of interrogator kit affixed to wall of rail operations center
EMTRAC Interrogator at a Rail Operations Center
  • Automatic Retrieval and Update: Wirelessly download activity logs from EMTRAC components, and automatically upload firmware or database updates to units that have not yet received the update.
  • Auto-Notifications: The EMTRAC software may be configured to email periodic activity logs to specified agency personnel.
  • System Monitoring: The EMTRAC software enables agency personnel to monitor connection status and history (between server and Interrogator as well as between Interrogator and EMTRAC components), and current RF signal strength.
  • Communication Stability: Data is not lost in cases of network interruption, and data transfers resume from the point of interruption.
Photo of interrogator kit affixed to wall of rail operations center
EMTRAC Interrogator at a Rail Operations Center
  • Minimal Wired Connections: For external connections, the EMTRAC Interrogator Kit requires only 120 VAC power and Ethernet. All communication with EMTRAC vehicle components is performed wirelessly.
  • Limitless Memory: By transferring activity logs to the system server, onboard EMTRAC components are able to continually store new log entries.
  • Timeliness: High transfer rates enable data transfers that take a relatively short period of time, offering many options for where to mount the Interrogator—such as near refueling or washing stations.
  • Flexibility: The EMTRAC Interrogator may be mounted on wall, pole, or other structure, and multiple antenna options allow for reliable communication in even high-interference environments.

Field Monitor Unit (FMU)

Photo of EMTRAC Field Monitor Unit (FMU)
ST-9286 Field Monitor Unit

System readiness starts at the control cabinet—and cabinets in remote locations are no exception. The Field Monitor Unit (FMU) includes cellular communications to provide access to detailed information about the status of the traffic cabinet. It also provides signal-priority detection and enables connectivity to multiple separate Ethernet-equipped systems within the traffic cabinet.

The Field Monitor Unit provides all the capabilities of EMTRAC Priority Detectors, with added support for traffic-controller monitoring capabilities. It offers multipurpose options for cities that seek to add Transit Signal Priority (TSP) and Emergency Vehicle Preemption (EVP) while also adding smart-city features to their wayside. These features include intersection and traffic-cabinet asset management, along with integration of the EMTRAC apps, such as our Bicycle Detection App.

Click here to open the Field Monitor Unit data sheet.

Photo of EMTRAC Field Monitoring Unit (FMU) in Cabinet
EMTRAC Field Monitoring Unit (FMU) in Cabinet
  • Signal Preemption and Priority (via Optical, RF, and Cellular)
  • Cellular-modem equipped
  • Two remotely-switched NEMA 5-15 power outlets
  • GNSS capable for location and controller timing updates
  • Battery back-up for coverage during power-outages
  • Compatible with EMTRAC Traffic Center software

Open the Field Monitor Unit data sheet for a more detailed rundown of FMU features and benefits.

Auxiliary Terminal Board

The EMTRAC Auxiliary Terminal Board provides a simple way to connect a wide range of electrical signals to and from the Priority Detector within the traffic cabinet. The ST-9751 auxiliary board includes two terminal-block rows to accommodate both inputs and outputs. The terminal blocks accept wire leads which are secured with screw-connection tension sleeves. All output terminals are 24VDC NEMA logic.

Connections to the Priority Detector are made through the 26-pin D-Sub port. The Auxiliary Board Interface Cable connects the auxiliary board to the Priority Detector.

Click here to open the auxiliary-board data sheet.


EMTRAC System video demonstrations of EMTRAC System capabilities, including Emergency Vehicle Preemption (EVP), Transit Signal Priority (TSP), transit rail safety, vehicle detection, and signal management.

Intelligent Signal Management  -  1:13