Triggering Trackside Equipment

Efficient asset management depends on reliable triggering of trackside equipment. It requires accurate collection of various data points such as the number of traversing axles, speed, direction, and the exact positioning of a wheel. Different applications are available to meet the various needs of all types of railroads, including AEI readers, hot box detectors, wheel impact load detectors and lubricators, to name a few.

When implementing a triggering system, the operator’s focus is to achieve high reliability and accuracy, maintain smooth operations, and obtain accurate asset management information. Ineffective or improperly functioning equipment can negatively impact operations, and ultimately the railroad’s bottom line. On the other hand, trackside equipment that is triggered effectively on a consistent basis saves the operator time and money, providing improved management of overall operations.

Challenges with commonly used triggering equipment

Negative effects from harsh environmental conditions


Common environmental conditions such as snow, rain, and fog can negatively impact the performance of equipment commonly used to trigger trackside equipment. Reliability issues that result from inaccurate detection and the need for frequent calibration can reduce the accuracy and effectiveness of asset management systems, increasing maintenance costs.

Frauscher Benefits

Not affected by harsh environmental conditions

Frauscher wheel sensors will continue to trigger trackside equipment reliably, regardless of adverse weather or environmental conditions. Rain, snow, fog, or severe temperatures that can affect other commonly used triggering equipment will not impact their performance, or trigger the need for frequent recalibration. The robustness and reliability of our wheel sensors allows the important functions of the trackside equipment to continue without interruption.

Sensitivity to electromagnetic interference and track return current


Electromagnetic interference and sensitivity to track return current can negatively affect the performance of some equipment commonly used for triggering trackside equipment.

Frauscher Benefits

Highly resistant to electromagnetic interference and track return current

Frauscher wheel sensors are recognized for being highly resistant to electromagnetic interference and track return current, which can negatively affect other sensors used for triggering trackside equipment.  Reliability and uptime will be maintained, despite the presence of these interferences that are commonly found in transit environments.


Time consuming and costly installation


Installation of several triggering equipment options requires drilling of the rail. This increases installation time and cost, increases worker time on track, and can negatively influence the integrity of the rail over time.

Frauscher Benefits

Quick and easy installation, no drilling

Frauscher wheel sensors are installed in just five minutes per sensor, using the Frauscher rail claw. The sensor is simply clamped to the rail, with no drilling of the rail required. This saves time and money, does not compromise the integrity of the rail, and increases safety by requiring less worker time on track. In addition, for applications such as warning systems that may benefit from mobility of the sensor, the rail claw and pluggable cable provide easy removal and subsequent relocation of the sensor as required.

Frequent sensor calibration requirements


Wheel sensors commonly used for triggering trackside equipment can require frequent recalibration due to several influences. Often this calibration must be done trackside and can be somewhat complicated to complete, requires special tools, and increases worker time on track.

Frauscher Benefits

Less frequent and remote calibration

Since Frauscher wheel sensors are not affected by environmental conditions or power interruptions, significantly less frequent recalibrations are required in comparison to other types of train detection equipment. The combination of Frauscher wheel sensors with the Frauscher Wheel Sensor Converter WSC provides the ability to recalibrate sensors remotely. The WSC offers customers the option to implement a command to calibrate the sensor via serial interface.

High frequency of maintenance cycles


When choosing activation devices such as wheel detectors for triggering trackside equipment, it is important to factor in the amount and frequency of required maintenance since there are significant differences among the options. Detectors used to trigger trackside equipment that require frequent maintenance will contribute negatively to the overall cost equation, and worker time on track.

Frauscher Benefits

Low maintenance requirements and lifecycle costs

Frauscher wheel sensors have the lowest recommended preventive maintenance cycle of any other trackside equipment triggering product available today. The requirement of just once in two years provides a maintenance cycle that is at least half as frequent as is required with the nearest competitive technology. Maintenance involves a quick operational and diagnostic check, which takes just minutes per sensor. The robust nature and low maintenance requirements of Frauscher wheel sensors save money and allow for increased safety, since workers are required to spend less time on track.

Compatibility issues with existing equipment


In situations where an operator needs to replace existing triggering equipment for any reason, they may wish to replace this equipment with another type of sensor. Equipment commonly used to trigger trackside equipment is often not compatible with other technologies. The only option for the operator is to change out all of the equipment or none, preventing the implementation of gradual changes or the advantage of a simple fix to a hot spot with a better performing product.   

Frauscher Benefits

Flexible integration

A significant advantage provided by Frauscher systems is the ability to seamlessly integrate with downstream controllers and other types of equipment. They offer the flexibility of providing analog or digital outputs, and they are also compatible with other types of triggering equipment. Operators have the option to implement a serial interface that allows status information to be retrieved. Outputs from the Wheel Sensor Converter WSC allows them to simulate a traversing to test upstream equipment and confirm proper triggering.


Slow train speeds, direction changes, stopping on wheel sensors


Several situations can occur that will cause many sensors or transducers used for triggering equipment to function improperly. Examples include trains that traverse the equipment at slow speeds, change direction, or trains that come to a stop while positioned on top of a sensor. The inability to operate at zero speed can cause equipment malfunction.

Frauscher Benefits

Zero speed capability

Frauscher wheel sensors offer true zero speed capability, a feature not available in other types of equipment used to trigger trackside equipment. This means that if a train stops directly on top of a sensor, the position and wheel count is maintained and the count will continue where it left off when the train resumes movement. This capability ensures equipment will be triggered properly, even in the event of zero speed movement.

Accuracy of detection, center pulse

The Frauscher Wheel Sensor RSR110 combined with the Wheel Sensor Signal Converter WSC provides accuracy of detection that is not possible with other types of triggering equipment. This high level of accuracy includes the ability to trigger an output at the exact point in time when the wheel is centered over the sensor, as exact positioning is vital to the proper function of trackside equipment. This accuracy of detection is also helpful in providing reliable speed measurement data.


Frauscher wheel sensors can address the important challenge of maintaining uptime and reliability for all trackside equipment triggering applications. They have been proven to provide optimum performance in all conditions, including snow, heavy rain, fog, or extreme temperatures, as well as in the presence of electromagnetic interference and for trains traveling at low to zero speed - unlike earlier available transducers that rely on a magnetic principle and are susceptible to these influences. Frauscher wheel sensors offer state of the art technology by operating on an inductive principle, a technology that is not subject to the frequent reliability issues common to magnetic sensors.

It is important that trackside equipment engages at the proper time. Frauscher wheel sensors provide a level of accuracy that is not possible with other types of triggering equipment. Combined with our Wheel Signal Converter WSC, the RSR110 wheel sensor can determine the exact center pulse of the wheel, ensuring accurate triggering.

Our wheel sensors are designed with an open interface to easily integrate with existing equipment and downstream controllers. This open interface, along with a simple installation process, ease of calibration (conducted trackside or remotely), low maintenance requirements and reliable technical support are just some of the advantages that contribute to the reliability of Frauscher wheel sensors when used to trigger trackside equipment.

Application areas

Automated Equipment Identification (AEI) Readers

Frauscher wheel sensors are utilized to trigger Automated Equipment Identification (AEI) readers to accurately identify vehicles. This process is vital to efficient and profitable operations and is dependent upon reliable and precise train detection. Legacy wheel sensors and transducers are susceptible to miscounts when exposed to deteriorated environmental conditions, current drifts or trains traveling at low speed, resulting in corrupted data. Rectifying the effects of a miscount is a “hands on” task for personnel, as the train must be stopped to manually resolve the discrepancy. These activities are time consuming, costly and increase worker time on track.

Reliable accuracy is the key benefit provided by Frauscher wheel sensors. Our sensors experience zero to few miscounts, as compared to older model transducers and wheel sensors that may have frequent miscounts. Frauscher wheel sensors can be easily incorporated into any AEI system to reliably trigger radio frequency identification (RFID) readers, delivering high accuracy regardless of the environment, presence of EMI, or trains traveling at low or zero speed.