Using technology taken from the automotive industry, a new driver assistance system for trams aims to increase road safety in urban areas, and take the first steps towards autonomous transit systems.
For tram drivers operating in city centers, complete concentration is required at all times, as heavy traffic conditions can lead to collisions with other trams, cars or trucks. Bosch has developed new technology that can actively prevent this type of accident, and the first trams featuring the system will shortly enter into service in the German city of Frankfurt. The innovative driver assistance system warns tram drivers of any impending collision: if the driver brakes too late, or not at all, the system engages the brakes independently to stop the tram and avoid an accident. The new, expanded system comes from Bosch Engineering, a subsidiary that has successfully adapted the company’s large-scale automotive production technology for its new and enhanced collision warning system for city rail transportation systems. The federal state of Hesse’s technical supervisory authority recently approved the electronic driver assistance system for use in public transportation, and once Frankfurt’s tram drivers have tested the new system for both drivers and passengers, the first self-braking trams will go into regular service in the city.
Already widely-used in the automotive industry, driver assistance systems that can warn of collisions and automatically brake in an emergency are increasingly spreading to rail transportation systems and will provide the basis for automated trams. The systems are capable of supporting the tram driver in all types of challenging driving conditions day or night, including heavy rain and snow, or fog. Bosch launched the first version of its collision warning system for trams in 2014, and the new and enhanced system takes the technology to another level. In the event that the driver cannot react to the warning in time, the system will now brake the tram automatically, and bring it to a complete stop.
The new collision warning system combines a video sensor, a radar sensor, and a high-performance rail control unit and draws on Bosch’s expertise in large-scale automotive production. With an aperture of up to 70°, the radar sensor monitors the area up to 525ft (160m) ahead of the tram, and measures the speed and distance of any cars, buses or other trams. The radar sensor also detects static objects, such as buffer stops. The video sensor is the ideal complement to the radar technology, because it keeps an eye on the track ahead and detects anything crossing the rails more quickly and accurately. The central rail control unit processes information from both sensors, along with other factors, such as the speed of the tram, to provide a detailed image of the environment. If the system detects that an object is coming dangerously close, it gives the driver a visual and acoustic warning. Should the tram driver not react to the warning signals within two seconds, the automated system slows the tram to a complete stop. The braking action is very gentle, so even passengers who are standing will not lose their balance.
“Our collision warning system significantly increases the safety of passengers and tram drivers,” said Bernhard Bihr, president of Bosch Engineering. “We are taking the idea of automated mobility further, beyond the road, and developing solutions that offer increased safety and comfort for rail transportation. Our system is on all the time; it never gets tired, and cannot be distracted.”