Priority-System Components

EMTRAC Transit Signal Priority

The EMTRAC system consists of three major components—vehicle equipment, wayside equipment (commonly installed at intersections), and the software used to configure and monitor the system.

Vehicle Equipment

EMTRAC Vehicle Computer Unit

VCU and Dual RF/Satellite-Positioning Antenna

Vehicle Computer Unit (VCU)

EMTRAC-equipped vehicles carry a compact, yet rugged, Vehicle Computer Unit (VCU), which is connected to a dual RF/satellite-positioning antenna that receives precise location data and transmits priority requests to wayside equipment via secure radio. The VCU tracks vehicle location with precision, and its superior range ensures reliable reception—even in adverse conditions.

Vehicles with the EMTRAC system transmit a priority request to equipped intersections when passing through pre-defined detection zones. The wayside signal-control cabinet contains an EMTRAC Priority Detector, which relays priority requests to the signal controller.

  • 900 MHz, frequency-hopping spread spectrum radio with secure, 256-bit AES encryption
  • Typical transmission range over 3,000 feet, enabling intersection-approach zones of the same length
  • Integrated computer board contains an ultra-fast processor and superior memory, while the MicroSD-card offers additional activity-log storage capability
  • Operates off nominal 10 to 40-volt DC power source with a maximum current of 500mA
  • Capable of communication through Ethernet, RS-232, or wireless connection
  • Sends four main directional codes, four auxiliary codes, while supporting up to 16 inputs and outputs in any combination
  • Capable of storing up to 5,000 intersection-approach zones
  • Ability to accept multiple inputs to prompt priority requests, including bus-door or pull-cord activity, schedule adherence, passenger count, and emergency light-bar
  • Time-out feature is configurable to cease transmissions after designated amount of inactivity
EMTRAC Onboard Control Head

EMTRAC Control Head Models

Control Head

The Control Head enables vehicle operators to monitor system activity and performance in real time. In addition to other features, drivers may be alerted when priority requests have timed out and when there is immediate potential for collision.

The Control Head is available in three models. The LED model (upper left) displays basic vehicle activity information. The Touchscreen model (upper right) displays both vehicle activity and specific alerts, such as collision-avoidance alarms. The Programmable model (bottom) displays vehicle activity, alerts, and may be used to change VCU configuration settings.

  • Indicates VCU is 1) actively receiving GPS signal, 2) the vehicle is currently in a detection zone, 3) the VCU is actively requesting signal priority, or 4) the priority request has timed out
  • May switch system to standby mode for monitoring/testing
  • Enables driver to reset timed-out priority requests
  • Warns driver of potential collisions with EMTRAC-equipped vehicles or personnel, as well as other designated alerts, such as if the vehicle is exceeding posted speed limits (touchscreen and programmable models)
  • May indicate that signal priority has been granted
  • Displays estimated time of arrival to defined points (touchscreen and programmable models)
  • Safety: Reduce collisions between equipped vehicles responding to the same emergency or on the same route by pro actively alerting drivers of potential hazards.
  • Efficiency: The program-capable model is equipped with a USB port, enabling agency personnel to load only intersections and detection zones for specific routes. It is also equipped with an Ethernet port, which may be used to download data or upload firmware updates.
  • Reliability: The touchscreen model enables drivers to reset timed-out requests to help clear intersections in even gridlock conditions.
  • Flexibility: The EMTRAC system may be installed on any vehicle type (first-response, buses, LRVs, snow plows, etc.), with control heads installed on only select vehicles.

Wayside Equipment

Wayside equipment includes the cabinet-mounted Priority Detector (available in RF, optical, and universal RF/optical models), the pole-mounted Omni-Directional Antenna, and the optional Vehicle-Interrogator Kit, which automatically downloads activity logs and installs firmware updates as needed.

EMTRAC TSP/EVP Priority Detector

EMTRAC ST-9283 Priority Detector

Priority Detector

The EMTRAC Priority Detector consists of 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.

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.

  • 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
EMTRAC Vehicle Interrogator Kit for TSP/EVP

EMTRAC Vehicle Interrogator Kit

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 FHSS radio to download activity logs from onboard EMTRAC units. This data is forwarded to a server running EMTRAC Central Monitor, 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.

  • 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.
  • 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.
EMTRAC Auxiliary Interface Panel

Auxiliary Terminal Board

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 accomodate 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 cut sheet.


Optical Equipment

RF/Optical Priority Detector

The ST-9365 Priority Detector is a dual-card, two or four channel universal phase selector to be used for encoded or non-encoded optical priority requests from all major brands of optical emitters, as well as EMTRAC 900 MHz FHSS radio.

EMTRAC Universal Phase Selector - Dual RF/Optical Priority Detector

ST-9365  -  Dual RF/Optical

The Priority Detector responds to frequencies from all major optical emitter brands, and it recognizes the frequency rates of requesting vehicles to differentiate their priority levels. The Priority Detector is capable of receiving both optical and RF requests and prioritizing them by priority level and class of vehicle.

The Priority Detector is compatible with NEMA, 170/2070, Caltrans, ITS, and custom cabinets. It can be installed directly into the input file of Type 170 controller cabinets or may be provided with a Priority Detector Case (ST-9194) for NEMA cabinets (when input-file space is not available).

  • Detects and calls up to four optical channels while simultaneously detecting EMTRAC RF requests
  • Records both optical and RF activity, logging each event by request type
  • Logs up to 5,000 locally-stored events (up to 10,000 events with removable memory)
  • Signal-phase monitoring and priority-request confirmation
  • Standby/Active switch enables testing and configuration without affecting the live signal
  • Multiple vehicle priority levels (to accommodate both EVP and TSP)
  • Compatible with all major brands of NEMA and 170/2070 controllers
  • Optically-isolated outputs (and auxiliary inputs)
  • Time to Hold Request After Loss of Signal
  • Max. Request Time/Min. Request Times (by channel)
  • Priority Service Control (define how simultaneous priority requests are served)
  • Communications Baud Rate
  • Configurable Output Channels (by direction)
  • Activity Log Display of Most Recent Events
  • Vehicle Allowance or Denial (by vehicle ID)
  • Optical Signal-Range Thresholds by Direction: Range up to 2,500 feet (3,000 feet in optimal conditions)
  • Audible Indicator (on Priority Detector): On or Off
Two & Four-Channel Optical Priority Detectors

The ST-9320 and ST-9340 Priority Detectors are single-card, two and four-channel devices to be used for encoded or non-encoded optical priority requests from optical emitters.

EMTRAC Two and Four-Channel Optical Priority Detectors

ST-9340 (4-channel) and ST-9320 (2-channel)

The Priority Detectors respond to frequencies from all major optical emitter brands, and recognize the frequency rates of requesting vehicles to differentiate their levels of priority. The Priority Detectors are capable of prioritizing simultaneous signal requests by priority level and class of vehicle.

The Priority Detectors can be installed directly into the input file of Type 170 controller cabinets or may be provided with a Priority Detector Case for NEMA cabinets (when input-file space is not available).

The ST-9320 and ST-9340 Priority Detectors are equipped with robust onboard memory and are capable of storing up to 5,000 detailed activity logs, which include Intersection ID, Vehicle ID*, Vehicle Class*, Vehicle Priority Level, Directional Code, Priority-Request Duration, Controller Confirmation (optional), and Request Start/Stop Date and Time.

*Vehicle ID and Class must be provided by emitting system.

  • Detects & calls up to four optical channels from all major brands of optical emitters.
  • Records vehicle-request activity, logging each event by request type
  • Logs up to 5,000 locally-stored events
  • Capable of monitoring and logging signal-phase states as well as priority-request confirmations
  • Standby/Active switch enables testing and configuration without affecting the live signal
  • Receives two-channel (ST-9320) and four-channel (ST-9340) ranging probe frequencies
  • Multiple vehicle priority levels (to accommodate both EVP and TSP)
  • Compatible with all major brands of NEMA and 170/2070 controllers
  • Optically-isolated outputs (and auxiliary inputs)
  • Time to Hold Request After Loss of Signal
  • Max. Request Time/Min. Request Times (by channel)
  • Priority Service Control (define how simultaneous priority requests are served)
  • Allow/Deny signal priority by Vehicle ID
  • Configurable Output Channels (by direction)
  • Vehicle Allowance or Denial (by vehicle ID)
  • Optical Signal-Range Thresholds by Direction: Range up to 2,500 feet (3,000 feet in optimal conditions)
  • Activity Log Display of Most Recent Events
Optical Sensors

The EMTRAC Optical Sensor detects optical strobe signals from vehicle-mounted emitters and outputs the interpreted signals to the cabinet-mounted EMTRAC Priority Detector.

EMTRAC Optical Sensors for Emergency Vehicle Preemption and Transit Vehicle Priority

Optical Sensors (1 dir, 2 dir, 2 dir/2ch)

EMTRAC Optical Sensors detect optical pulses from both EMTRAC and non-EMTRAC vehicle emitters. The Optical Sensor is fully compliant with NEMA TS2 standards and is encapsulated in a rigid weatherproof enclosure and is supplied with all hardware and sealing gaskets.

The Optical Sensor may be mounted on mast arms, span wire, or other appropriate structure with a direct, line-of-sight view of the intersection approach.

The EMTRAC Optical System is the preferred method for signal-priority control for agencies looking to update existing optical systems, while adding the ability to detect multiple types of legacy emitters.

For more detailed specifications, refer to the Optical Sensors cut sheet (PDF).


System Software

EMTRAC Central Monitor - Automatic Vehicle Location for Transit Signal Priority and Emergency Vehicle Preemption

Central Monitor Real-Time Activity Map

Transit and first-response agencies are able to take full control of their priority system by utilizing the EMTRAC software.

This software includes EMTRAC Systems Manager, which is used to configure all of the components of the EMTRAC system. It is where you define the vehicles, intersections, and zones that will be utilized for your priority system—and where you specify how the vehicle and wayside equipment will respond in different scenarios. While the EMTRAC system is relatively simple to set up, it is also robust enough to handle complex applications.

EMTRAC Central Monitor is an Automatic Vehicle Location (AVL) service that displays precise vehicle activity and much more. Additional Central Monitor capabilities are listed below.

  • Map display of city streets, showing location and activity for all equipped vehicles.
  • Ability to monitor vehicle "events" by user-definable types. For example, when used to monitor light rail activity, the system can be set up to log stop-bar overruns.
  • Audible and pop-up alarms notify control center personnel of critical events (such as a light rail vehicle on the wrong tracks).
  • Automatically generate user-definable reports, which can be automatically archived and/or emailed at defined intervals
  • Verify proper system functionality by monitoring signal-controller responses to priority requests.
  • Remotely check EMTRAC system diagnostics to verify proper functionality.
  • Detect and confirm proper rail crossing-gate closure. If a gate fails to close, an alarm may be sent to the control center and vehicle driver.
  • Ease of Monitoring: Know where equipped vehicles are in real time.
  • Low-Maintenance: Reliable vehicle positioning and RF communication requires no in-ground loops or costly switches.
  • Reporting: Generate detailed status and activity reports, as well as connectivity reports.
  • Safety: Alert monitoring personnel about potentially unsafe vehicle activity in real time.
  • Flexibility: Customize detection zones and necessary parameters to transmit desired vehicle activity data.
  • Timeliness: Improve schedule adherence and emergency response times by requesting signal priority when agency-specified conditions are met.
  • Security: Frequency-Hopping Spread Spectrum radio signal has expansive range and utilizes AES encryption.
  • Accuracy: Monitor vehicle activity with precise and current location data.