Railway safety and efficiency rely heavily on advanced thermal sensing technologies, particularly infrared (IR) sensors, which play a vital role in detecting obstacles, monitoring rail conditions, and preventing accidents. To delve deeper into the significance and applications of IR sensing in modern railway operations, continue reading.
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An Introduction to Thermal Sensing in Railroad Operations
Infrared sensors utilize infrared technology to detect objects and environmental variations 1. Modern railway systems use different types of IR sensors, such as Passive IR sensors, reflective sensors, transmissive IR sensors, and IR temperature sensors, to ensure the safety of passengers and guarantee efficient and smooth railway operations 2.
Importance of Infrared Thermal Sensing for Rail Safety
In the railway industry, thermal monitoring plays a crucial role in minimizing unscheduled breakdowns of undercarriage elements, thereby preventing costly failures and downtime 2. In this context, using infrared technology is considered the best solution for temperature measurement 3.
Modern systems in the railway industry incorporate accurate infrared thermal scanners as part of an automated inspection and measuring system. These scanners are often mounted on gates over the rail tracks to perform thermal analysis of trains 3, 2. Advanced infrared sensors in these systems utilize state-of-the-art multi-element photovoltaic detectors. These detectors are specifically designed to achieve high measuring system accuracy and reduce the occurrence of false alarms.
Furthermore, IR detectors are used for continuous monitoring of overhead catenary in modern railways, as when wires become loose, it can lead to failure. Infrared sensors and infrared imaging cameras are used for continuous monitoring of the catenary to ensure proper working.
Applications of Infrared Thermography for Structural Health Monitoring of Railroad Surfaces
In the railway industry, serious rail accidents often result from defects occurring at the rail head due to rail-wheel contact. Fatigue loading generated by this contact leads to plastic deformation of the rail head steel, resulting in surface flaws of various orientations and dimensions 4. Additionally, constricted elongation of welded rails, along with residual stresses from manufacturing and in-field welding, generates thermal stresses.
Characterizing rail head flaws poses challenges due to their clustered distributions and geometric interactions. As per the article published in Case Studies in Thermal Engineering, infrared thermography (IRT) has gained attention for its advantages, including non-contact sensing and simple visualization of minor thermal variations compared to other methods 4.
IRT proves to be a valuable tool for detecting and assessing rail head flaws in a non-intrusive manner. Researchers used IRT for qualitative characterization and detection of railroad surface defects, including transverse and longitudinal flaws. The obtained results offer a quantitative evaluation of surface flaws on different types of railroad surfaces that are subjected to operational wear and harsh environmental conditions. This quantitative assessment is crucial for maintaining the safety and reliability of railway infrastructure.
Advantages of Using IR Sensors for Obstacle Detection in Railway Systems
Environment perception is a critical aspect of autonomously detecting obstacles in a vehicle's surroundings 5. The utilization of onboard sensors in road vehicles for this purpose is well-established. Advances in Artificial Intelligence (AI) and sensing technologies have spurred substantial research and development efforts in obstacle detection 5.
As per the article published in sensors, in an object detection (OD) system, an infrared camera and a laser rangefinder are embedded in the train system. A modern multi-sensor IR configuration, comprising three video cameras and an infrared radar system, is deployed to monitor the track ahead of a train 5.
Various combinations of sensors, including stereo vision, monocular cameras, radar, and laser, are commonly integrated into the train's detection system. Advanced infrared multi-system sensing technology incorporates forward-looking infrared (IR) sensors, optical passive video cameras, and LiDAR. These sensors operate based on the time-of-flight principle, ensuring high longitudinal precision 5.
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Major Benefits and Advantages of Infrared Sensing
In contrast to other sensing technologies, IR sensors offer cost-effective and straightforward installation 6. They demonstrate effective performance in diverse weather conditions, including low light and extreme temperatures. A crucial application of IR beams in railway systems involves triggering warning signals and closing barriers when a train approaches a level crossing. This enhances safety for both road users and pedestrians.
Train collisions can be categorized into direct, rear-to-end, and side-to-side collisions. Anti-collision/avoidance systems employ infrared sensors along with ultrasonic sensors, microcontrollers, and GSM technology to prevent train accidents 7. In this system, infrared sensors play a crucial role in detecting track cracks. The setup typically includes a transmitter and a receiver that communicate through infrared signals 7, 4.
What Does the Future Hold?
Researchers are trying to develop infrared sensors with a higher tolerance for environmental effects like dust. Recently, a new infrared sensor has been developed that can detect even stationary objects, unlike conventional passive IR sensors that can only detect moving objects 8.
Additionally, modern additive manufacturing and nanotechnology have enabled the fabrication of ultra-precision sensors, which require very little power to operate. Additionally, the progress of AI and data analytics software is enabling the manufacturing of IR sensors with embedded data management platforms to analyze their performance efficiently.
Infrared sensing plays a pivotal role in modern railway operations, assuring safe, efficient, and reliable train operations. Integrating modern IR sensors in the advanced Internet of Things (IoT) platforms has massively increased the popularity of the new intelligent railway management systems. These systems increase the safety of the passengers and the train while making railway operations economical and sustainable.
References and Further Reading
- Electronicsforu (2023). Understanding IR Sensors and IR LEDs: Functions, Differences, and Applications. [Online]. Available at: https://www.electronicsforu.com/technology-trends/learn-electronics/ir-led-infrared-sensor-basics. [Accessed 3 January 2024].
- Vigo Photonics (2022) Infrared Detectors for Railway Transport Safety. [Online]. Available at: https://vigophotonics.com/applications/infrared-detectors-for-railway-transport-safety/ [Accessed 02 January 2024].
- Ulrivision Technology (2023) Application of Infrared Thermal Camera in Monitoring of Railway Overhead Line System [Online]. Available at: https://www.ulirvisiontech.com/application-of-infrared-thermal-camera-in-monitoring-of-railway-overhead-line-system.html. [Accessed 04 January 2024].
- Ramzan, B. et. al. (2021). Pixel frequency-based railroad surface flaw detection using active infrared thermography for structural health monitoring. Case Studies in Thermal Engineering, 27, p. 101234. doi.org/10.1016/j.csite.2021.101234
- Ristić-Durrant D. et. al. (2021). A Review of Vision-Based Onboard Obstacle Detection and Distance Estimation in Railways. Sensors. 21(10). p. 3452. doi.org/10.3390/s21103452
- Healthcote Electronics (2023) How infra red train detection works (2023). [Online]. Available at: https://www.heathcote-electronics.co.uk/how_infra_red_model_train_detection_works.html. [Accessed 4 January 2024].
- Singh, M. et. al. (2022). Anti-Collision Systems For Trains. Proceedings of the International Conference on Innovative Computing & Communication (ICICC) 2022. Available at: https://dx.doi.org/10.2139/ssrn.4345645
- STMicroelectronics (2023) STMicroelectronics reveals innovative infrared (IR) sensor for presence and motion detection in building automation. [Online]. Available at: https://newsroom.st.com/media-center/press-item.html/p4562.html. [Accessed 4 January 2024].
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