Autonomous Emergency Braking Systems

In Canada during 2013, 26% of all victims injured and 4.5% of all victims killed in reportable traffic collisions incurred their injuries in rear-end collisions (Transport Canada, 2016). Autonomous emergency braking (AEB) systems have been developed to help drivers avoid rear-end crashes or to reduce the severity of these types of collisions if they do occur.

Autonomous emergency braking (AEB) systems use radar, camera and/or lidar-based technology to identify potential collision objects in front of a vehicle in combination with vehicle travel speed and trajectory to determine whether or not a critical situation exists, and if does, warns the driver. If the driver does not react following the warning and a collision is imminent, the system then applies the brakes.

Cicchino (2016) carried out a study to estimate the effect on police-reported crash and casualty rates of AEB-equipped Volvo passenger vehicles, which brake autonomously at speeds up to 19 mph. Police-reported crash rates per insured vehicle year in 27 U.S. states during the 2010-2014 period were compared between select 2010-2012 AEB-equipped Volvo models and other luxury midsize passenger vehicles without the system, controlling for other factors affecting crash risk. The results of the analysis showed that the rear-end striking crash involvement rate was 41% lower for the AEB-equipped Volvos, and 47% lower for rear-end striking crash involvements that resulted in injuries. Overall, the AEB-equipped vehicles had 14% lower crash involvement rates, 13% lower involvement in multi-vehicle collisions, and 12% lower injury-producing crash involvement rates. The largest reductions in rates of all rear-end striking crash involvements occurred on roads with posted speed limits of 40-45 mph (54%).

Fildes et al. (2015) carried out a meta-analysis of crash data from several European countries to evaluate the effectiveness of low speed AEB technology in current model passenger vehicles. The findings of the study showed that vehicles fitted with AEB technology had 38% fewer rear-end crashes than a comparison sample of similar vehicles, and that the technology was effective in reducing crashes in both urban (<=60 km/h) and rural (>60 km/h) speed zones. The authors of the study recommended widespread fitment of low speed AEB technology in order to achieve maximum benefits.

Rizzi et al. (2014) evaluated the effectiveness of AEB technology at reducing rear-end crashes. The study involved the analysis of 2010-2014 police-reported crash data from Sweden. In the study, crash-involved Volvo passenger cars equipped with AEB were compared with similar-type Volvo’s not equipped with AEB as well as with other non-AEB equipped cars from other manufacturers. In the study, striking vehicles involved in two-vehicle rear-end crashes were deemed sensitive to AEB. Vehicles struck in two-vehicle rear-end crashes as well as all crossing crashes were considered non-sensitive to AEB. The results of the research showed that AEB equipped vehicles were involved as the striking vehicle in 54%-57% fewer rear-end crashes in 50 km/h or lower speed areas than comparison vehicles. There was also a 35%-41% reduction in striking-vehicle rear-end crashes when comparisons were made for all posted speed limits.

Doyle et al. (2015) analysed the impact of AEB on claim losses using actual insurance claims data in the United Kingdom. Statistical regression was used to compare the claims losses for Volvo XC60 model vehicles, which are equipped with low-speed AEB technology called City Safety, to that of a SUV control cohort of vehicles without AEB technology, and to quantify any AEB effects identified. The analysis showed that the estimated claim frequencies for the XC60 were 8% lower for third party damage, 6% lower for own damage, and 21% lower for third party injury. Claim damage severity was also estimated to be 10%-15% lower for the XC60 vehicles relative to the control cohorts.

Moore et al. (2013) compared insurance claim records of vehicles equipped with optional forward collision avoidance features, including autonomous emergency braking, with records for the same vehicles without these to estimate their effectiveness. The effects of each vehicle feature were quantified using regression analysis. Claim severity and overall losses were derived from the frequency and severity models. The results of the analysis showed that collision avoidance systems with autonomous braking resulted in 10%-14% reductions in the frequency of claims to repair damage that the striking vehicles caused to other vehicles.

Anderson et al. (2013) carried out an AEB simulation project that analysed fatal and injury crashes from an Australian in-depth crash database.  Crash reconstruction was carried out to determine collision speeds at impact and simulations were carried out to estimate the potential effectiveness of several AEB systems at reducing collision speeds and injury risks. The results of the simulation, which assumed universal operability and reliability of the systems, indicated that AEB has the potential to reduce fatal crashes by 25-25% and injury crashes by 25%-35%. The authors of the study noted that, depending on their performance parameters, AEB systems’ potential to completely avoid crashes were highest for pedestrian crashes and rear-end collisions.

Paez et al. (2015) assessed the potential effectiveness of AEB in a small sample (50) of injury producing vehicle-pedestrian collisions that occurred in Madrid, Spain. Crash data were analysed and reconstructed through simulations to estimate collision speed and pedestrian kinematics. The performance of AEB system was simulated to assess the potential reduction in collision speed and injury severity between the actual crashes and the simulated crashes. The results of the study indicated that 42% of the collisions could have been avoided if the vehicles involved in the crashes had been equipped with brake assist systems, antilock brakes and AEB systems.

Rosen (2013) carried out research aimed at assessing AEB performance in vehicle-pedestrian and vehicle-cyclist crashes where some of the more relevant system parameters (braking capacity, darkness, speed) were varied. Data modelling was used to create a reference AEB system that was highly effective in avoiding fatalities and reducing injury severities. The results of the study indicated that the AEB effectiveness was highly sensitive to system parameters defining brake capacity as well as functionality in darkness and at high speed. The model examined six AEB systems. The minimum system in the study, which combined all of the restrictions (darkness, high speed, timing and deceleration), was ten times less effective than the reference system at avoiding fatalities and reducing injury severities.

In Canada, Transport Canada is currently evaluating the performance of AEB systems to determine minimum performance requirements, to develop standard test procedures, and to estimate their potential for reducing the number and severity of targeted crashes.

Scope of Problem:

• Transport Canada (2016). 2013 National Collision Database, Transport Canada. Retrieved from: http://wwwapps2.tc.gc.ca/Saf-Sec-Sur/7/NCDB-BNDC/p.aspx?i=17005&l=en&wk=4#o1  

Evidence:

• Cicchino, J.B. (2016). Effectiveness of Volvo’s City Safety Low-Speed Autonomous Emergency Braking System in Reducing Police-Reported Crash Rates. Insurance Institute for Highway Safety, Arlington, VA. Retrieved from: http://www.iihs.org/frontend/iihs/documents/masterfiledocs.ashx?id=2112
• Fildes, B., Keall, M., Bos, N., Lie, A., Page, Y., Pastor, C., Pennisi, L., Rizzi, M., Thomas, C., & Tingvall, C. (2015). Effectiveness of low speed autonomous emergency braking in real-world rear-end crashes. Accident Analysis & Prevention, Volume 81, August 2015, Pages 24-29. Retrieved from: http://www.sciencedirect.com/science/article/pii/S0001457515001116
• Rizzi, M., Kullgren, A., & Tingvall, C. (2014). Injury crash reduction of low-speed Autonomous Emergency Braking (AEB) on passenger vehicles. Proceedings of the 2014 IRCOBI Conference, Berlin, Germany. Retrieved from: http://ircobi.org/downloads/irc14/pdf_files/73.pdf
• Doyle, M., Edwards, A., & Avery, M. (2015). AEB real-world validation using UK motor insurance claims data. Proceedings of the 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). Paper no. 15-0058. Retrieved from: http://wbldb.lievers.net/10137503.html
• Moore, M., & Zuby, D. (2013). Collision Avoidance Features: Initial Results. Proceedings of the 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV), Seoul, Korea. Paper no. 13-0126. Retrieved from: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv23/23ESV-000126.PDF
• Anderson, R., Doecke, S., Mackenzie, J., & Ponte G. (2013). Potential Benefits of Autonomous Emergency Braking Based on In-Depth Crash Reconstruction and Simulation. Proceedings of the 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV), Seoul, Korea. Paper no. 13-0152. Retrieved from: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv23/23ESV-000152.PDF
• Paez, F.J., Furones, A., & Badea, A. (2015). Benefits Assessment of Autonomous Emergency Braking Pedestrian Systems Based on Real World Accidents Reconstruction. 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). Gothenburg, Sweden. Retrieved from: http://trid.trb.org/view.aspx?id=1357849
• Rosen, E. (2013). Autonomous Emergency Braking for Vulnerable Road Users. Proceedings of the 2013 IRCOBI Conference, Gothenburg, Sweden. Retrieved from: http://www.ircobi.org/downloads/irc13/pdf_files/71.pdf