Towards Crash-Free Driving: Opportunities and Limitations of Automated Emergency Braking in Intersections

Licentiatavhandling, 2018

Intersections are a global traffic safety concern. In the Unites States, about half of the fatal road traffic accidents take place at intersections or were related to them. In the European Union, about one fifth of the road traffic fatalities occur at intersections. In Japan, crossing accidents resulting in fatality or severe injury account for over a quarter of all accidents.

Vehicle-to-everything (V2X) communication seems to be a promising technology to encounter intersections accidents, because its functionality is unaffected by sight obstruction. However, conflict involved vehicles have both to be equipped with this technology, otherwise communication cannot take place. On-board sensing, such as information retrieval via vision systems or radar is operational on its own. Intersection AEB function based on on-board sensing can be designed with a wide range of parameter settings, affecting the real-world performance of such a system.

This thesis investigates the effectiveness of four crash avoidance technologies with V2X communication and with on-board sensing using data from the United States National Automotive Sampling System Global Estimates System and from the Fatality Analysis Reporting System. To estimate the number of saved lives for each of the technologies, quantities of addressable accidents derived in another study were taken as a reference and combined with a market penetration model. Using two different scenarios for market penetration increase per year it was shown, that on-board sensing has a substantial higher capability to save lives until 100 percent market penetration is reached.

Therefore, the effect of different Intersection AEB system parameters on accident avoidance using on-board sensing was further analyzed. Data from the German In-Depth Accident Study and the associated Pre-Crash Matrix were used to re-simulate a sample of 384 left-turn across the path accidents with oncoming traffic. The result showed that driver comfort boundary settings have a strong impact on the ability of the Intersection AEB to prevent accidents. A substantial increase of avoidance potential was achieved, when escape paths could be excluded. At speeds higher than 40 km/h avoidance was hardly possible for the turning vehicle. Sight obstructions were not accurately represented in the input data, thus the resulting small decrease of system effectiveness by obstruction may not be accurate. It is expected, that Intersection AEB in combination with V2X shows a substantially higher benefit than AEB on its own.