Temperature Monitoring of Trucks to Improve Road Safety

How thermal imaging cameras detect thermal anomalies in brakes, axles, and wheels at an early stage and support vehicle inspections

Challenge

Defective braking systems, overheated wheel bearings, and underinflated tires pose significant safety risks in heavy-duty transportation. Conventional visual inspections often fail to reliably detect thermal anomalies. The challenge is to monitor safety-critical vehicle components quickly and without contact during vehicle access inspections, eliminating the need for time-consuming manual checks.

Solution

At inspection stations, trucks pass a ground-level Optris thermal imaging camera at walking speed. The camera captures the temperature distribution of brakes, axles, and wheels. By comparing defined measurement areas on both sides of the vehicle, unusual temperature differences can be detected, potential defects identified, and targeted follow-up inspections initiated.

Benefits

Early detection of thermal anomalies reduces potential accident risks and improves road safety.
Non-contact temperature inspections enable rapid checks of safety-critical vehicle components without extensive manual intervention.
Comparing both sides of the vehicle helps identify defective or unevenly operating braking systems.
Immediate evaluation enables targeted follow-up inspections and improves the efficiency of vehicle checks.
Documenting thermal anomalies supports informed decisions regarding necessary maintenance and safety measures.

Early Detection of Safety-Critical Defects in Trucks

Road safety in heavy-duty transportation largely depends on the technical condition of vehicles. Braking systems, axles, and tires in particular are exposed to high mechanical and thermal loads during daily operation. Defective or poorly maintained components can have serious consequences. The braking systems of truck trailers present a particular challenge. If they do not function properly, for example due to faulty connections, inadequate maintenance, or technical defects, the braking performance of the entire vehicle can be significantly reduced. Overheated wheel bearings, dragging brakes, or underinflated tires can also create dangerous situations.

Reliable inspection procedures are required to identify such risks at an early stage. These procedures should assess the technical condition of safety-relevant vehicle components as quickly and efficiently as possible. Conventional visual inspections are often insufficient because thermal anomalies cannot be seen directly. Manual temperature measurements of individual components are also time-consuming and provide only limited information.

A particularly important parameter is the temperature distribution in the braking system. Braking generates heat. When brakes function correctly, temperatures at comparable positions on the vehicle axles should develop similarly. If the expected temperature increase does not occur at individual brakes, this may indicate insufficient braking performance. Significantly elevated or unevenly distributed temperatures, on the other hand, may indicate dragging brakes, overloaded components, or other mechanical problems.

Operators of inspection stations face the challenge of detecting these temperature differences quickly and reliably. Measurements must accommodate different vehicle types, axle configurations, and vehicle heights. In addition, inspections should be easy to integrate into existing procedures without major modifications or extended downtime. Non-contact temperature measurement is particularly suitable for highway inspection stations, where trucks pass slowly and deliberately through a defined measurement position.

Thermographic Undercarriage Inspection with the optris PI 640i

The industrial thermal imaging camera optris PI 640i is suitable for non-contact temperature monitoring of vehicle undercarriages. Unlike an infrared thermometer, which measures only a single point, it captures the temperature distribution across an entire field of view. This allows several important vehicle areas to be inspected simultaneously, even when different truck models pass through the inspection station in slightly different positions. The PI 640i offers an optical resolution of 640 × 480 pixels and a frame rate of 32 Hz, providing detailed thermal images. For faster measurement tasks, an additional subframe mode with 640 × 120 pixels at 125 Hz is available.

In this application, a single thermal imaging camera is installed in a protected position close to the ground at the inspection station. A retractable or hinged protective structure allows the camera to be moved into the measurement position when required. Outside inspection periods, the structure protects the camera from mechanical impacts. During measurement, the camera views the vehicle diagonally from below while the truck passes through the inspection point at walking speed. The distance between the camera and the measurement target is only a few meters. The optionally available wide-angle lens with a field of view of 120° × 100° captures a large area of the vehicle undercarriage.
The PI 640i operates in the spectral range of 8 to 14 µm. It offers various temperature measurement ranges from −20 °C up to 900 °C. Measurements up to 1,500 °C are also optionally available. A thermal sensitivity of 60 mK with the 120° lens enables the detection of small temperature differences.

The camera connects to a laptop via USB 2.0, which also supplies power. The free optris PIX Connect software enables live visualization and evaluation of thermal images. Two predefined measurement areas record the temperature profiles of the left and right wheel or brake sections. A temperature-time diagram facilitates direct comparison between both sides of the vehicle, allowing anomalies to be identified immediately. The radiometric measurement data can be stored for subsequent analysis. Complex integration into larger control systems is not required for this measurement setup.

Efficient Vehicle Inspections and Early Detection of Safety Risks

With the optris PI 640i, operators of vehicle inspection stations can detect safety-relevant temperature deviations in trucks at an early stage. Large-area thermographic monitoring enables rapid assessment of braking systems, axles, and wheels without requiring individual components to be inspected manually beforehand. Comparing temperature profiles on both sides of the vehicle provides particularly valuable indications of potential faults. Both unusually high temperatures and the absence of an expected temperature increase can be detected and investigated.

One important advantage is the ease of operation of the measurement system. The PI 640i features a compact design, measuring just 46 × 56 × 76 to 100 mm. This allows the camera to be integrated into ground-level inspection equipment even where installation space is limited. The direct USB connection, power supply via the same interface, and free analysis software reduce installation effort and system costs. The camera can be deployed when needed and subsequently removed from the inspection equipment.

Live evaluation helps inspection personnel immediately identify suspicious vehicles for further technical examination. Storing radiometric recordings allows detected anomalies to be clearly documented. This simplifies inspection procedures and enables potentially dangerous vehicle conditions to be identified before they lead to accidents.
Optris offers additional options for automation. For example, temperature-dependent alarm signals can be transmitted via the industrial process interface, automatically alerting inspection personnel to anomalies. The optional USB Server Gigabit 2.0 also enables the camera to be connected via a network, allowing greater flexibility in positioning the evaluation station.

The measurement principle can also be applied to other types of vehicles, such as buses, vans, or rail vehicles. Industrial infrared measurement technology from Optris therefore provides a versatile solution for condition-based vehicle inspections, making a significant contribution to improving road safety.

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