Automatic braking at intersections
Crossroads and junctions are the most complex part of the modern traffic environment. When many road-users cross each other’s paths simultaneously and from different directions, all that is needed is a small mistake to cause a serious accident.
In the USA, 21.5 percent of all fatal accidents in 2007 occurred in intersections, and in 16 EU countries (excluding Sweden) the corresponding figure was 20.6 percent in 2006.
Mattias Brännström, PhD Active Safety Functions, is responsible for Intersection Support, a research project within Volvo Car Corporation in collaboration with the Department of Signals and Systems at Chalmers University of Technology. The system alerts and automatically brakes for crossing traffic when necessary (see the graphics and video).
« Intersection Support uses sensors to assess the entire traffic scenario. If a critical situation is registered, a decision to intervene is taken at lightning speed, » explains Mattias Brännström.
He exemplifies this by drawing a queue of cars turning left at an intersection. When the light turns green one car after another turns left. Suddenly an oncoming car drives through the red light – and creates an immediate danger.
« In this situation, the turning car automatically brakes to avoid a collision. Intersection Support thus serves as a system that not only helps deal with the driver’s own mistakes, but those of other road users too, » explains Mattias Brännström.
He says Volvo Car Corporation’s safety approach is about getting cars to behave like people. The sensors are the eyes, the computers are the brain and the brakes are the muscles.
« With our advanced technology we’re trying to do the same thing that people would do in the same situation if they have time to react. We want to provide assistance in as many situations as possible, » says Mattias Brännström.
In order to obtain the necessary data for the development of these systems, cars are driven hundreds of thousands of kilometres in various traffic environments the world over. After all, the system has to be equally capable of helping drivers in Bangkok and Vancouver – and in a way that is tailored to local variations in driving style and traffic intensity.