Sensors for Environmental Perception

Thanks to Smart Sensor Technology, Trains have an Eye on their Surroundings at all Times


To digitize the railroad system, technology is required that can detect the train’s surroundings. For this purpose, high-performance sensor technology (camera, Lidar & radar) is used in and on the train. Technical realization is achieved by sensors mounted on the front of the train. Such a multi-sensor setup consists of several cameras to cover the visible wavelength range, which alongside image data can also determine depth values of the environment at close range (stereo cameras), together with cameras that cover medium and long visibilities (approx. 300-550 m). These are supplemented by Lidar sensors that “scan” the field of view using laser technology. Moreover, an infrared camera also detects objects using the long-wave infrared spectrum, thereby facilitating environmental perception irrespective of the lighting conditions. The environmental perception sensor set is completed by adding radar sensors. All raw sensor data is processed and consolidated by a high-performance server system. In the future digital railroad system, data on irregular incidents will be transmitted in real time to the operations centers, where it will be analyzed and measures initiated to re-stabilize the traffic flow.

The Advantages at a Glance

An environmental detection system allows the surroundings to be observed and analyzed in real time. This enables the train to continuously assess whether or not objects should be classified as obstacles. This enables a faster response to external influences. Together with ATO (Automatic Train Operation), environmental perception is the most important building block for driverless, fully automated driving, and is responsible for monitoring the route. Combined with a digital map and precise location sensing, environmental perception can be used to determine the exact location of the train.

The Technology in Action

The Sensors4Rail cooperation project between Deutsche Bahn, Bosch Engineering, HERE Technologies, Ibeo Automotive Systems (now MicroVision), and Siemens Mobility is engaged in testing environmental perception technology. This involves recognizing the track’s course and correlating it with the driving situation and surrounding objects to determine the correct reactions. A Hamburg S-Bahn train was already equipped with the corresponding sensor technology in August 2021. The results were presented during special runs along the S21 line’s 23-kilometer route between Hamburg-Berliner Tor and Bergedorf at the 2021 Intelligent Transport Systems (ITS) World Congress in Hamburg.

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