Collision Avoidance: Smart Trams Think Ahead

A recent collision in Graz, Austria, involving a tram and a police car has underscored the critical need for advanced safety systems to prevent accidents between rail vehicles and other traffic participants.

The incident occurred when a police car entered an intersection and had to brake suddenly for an oncoming cyclist. The following tram driver apparently failed to notice the braking police car in time, and an emergency stop could not prevent the collision, resulting in minor injuries to the police officer. Such accidents can often be far more severe due to the considerable size and weight of trams, which typically weigh around 60 tons when fully occupied, making them formidable compared to other road users.

To address this persistent safety concern, various assistance systems have been developed over the years. Notably, the first and most comprehensive of these systems originated in Austria. The impetus for this development came from discussions with the Frankfurt Transport Company in Germany, according to Gerald Newesely, who holds strategic leadership positions in the rail vehicle sector at Alstom.

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You know it from Westerns: when the steam locomotive accelerates, the wheels spin, sparks fly. And when braking, the wheel locks, and they fly again.

Researchers at the Austrian Institute of Technology (AIT) in Vienna pioneered the use of cameras for obstacle detection, testing their StereoVision technology for three-dimensional perception on a rail vehicle for the first time approximately 15 years ago. This initiative aimed to enhance rail safety, drawing parallels to existing assistance systems in cars.

However, applying such technology to trams presents unique challenges. Unlike cars, trams cannot swerve to avoid obstacles. Their considerable weight and steel wheels on rails result in long braking distances. Newesely explained the dilemma: "You know it from Westerns: when the steam locomotive accelerates, the wheels spin, sparks fly. And when braking, the wheel locks, and they fly again." Furthermore, tram drivers are responsible for up to 250 passengers, posing a complex ethical question, often referred to as the 'Trolley Problem,' about risking the health of many to avoid hitting an obstacle.

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With a B driver's license, you are responsible for yourself and a maximum of seven people; as a tram driver, for up to 250. You have to decide whether, to save an obstacle – whether living or not – you risk the health of these many people if they are thrown from their seats and fall around.