The number of passenger cars equipped with Auto Brake functionalities in traffic is increasing rapidly. Following this, the opportunity to study real world performance of these systems is growing. The low-speed Auto Brake system City Safety, launched in 2008 and a standard feature on all recent Volvo Cars’ models, is a technology designed to help the driver mitigate and in certain situations avoid rear-end collisions at low speed by automatically braking the vehicle. Previous analysis of the City Safety technology showed promising results in terms of reducing real world crashes.

In this study, further evaluation of City Safety was performed based on insurance claims data. Using a unique dataset containing all new Volvo cars in traffic in Sweden from 2010 to 2014, including the possibility to control for other advanced driver assistance systems such as ACC, FCW and Auto Brake functionalities, the rate of rear-end frontal collisions per insured vehicle years was studied. First, car models with and without City Safety were compared. Second, the same car model with and without City Safety was compared, thereby controlling for specific characteristics in different models. Finally, the second generation of City Safety, that operates at speeds up to 50 km/h, was compared to the first generation (<30 km/h). Results showed that the overall claim frequency of rear-end frontal collisions was 28% lower for City Safety equipped models than for other Volvo models without the system. The result of the comparison between the same models was similar while no significant collision avoidance effect of the upgraded system to speeds up to 50 km/h was found. The expected crash mitigating effect of City Safety can be added to these results, providing a further potential to be explored in future real world follow-up studies.

This study confirms previous encouraging results of the crash reducing effect of the City Safety functionality. The findings of Auto Brake safety performance in real world traffic, shows the relevance of this type of vehicle systems for increased traffic safety and emphasizes the importance of the introduction of such systems on the market.