Run off road safety

Jakobsson, Lotta; Axelson, Anders; Björklund, Magnus; Nilsson, Pär; Victor, Trent

Affiliations

Abstract

Run off road events are frequent and can result in severe consequences. The reasons for leaving the road are numerous and the sequence the car is subjected to differs in most events. The aim of this study is to holistically address safety improvement in run off road events, presenting methods for evaluation as well as examples of countermeasures for the whole sequence from normal driving to post-crash.

Real world data, comprising statistical and in-depth crash data as well as driving data from Volvo Cars’ database in Sweden, forms the basis for understanding of influencing factors and mechanisms related to occurrence of the event as well as occupant injury. Countermeasures are presented along with the test methods which were developed based on the mechanisms identified. The test methods include road off road avoidance test methods, complete vehicle crash tests, and rig tests; such as occupant positioning using a robot rig and vertical loading tests using a drop tower rig.

Countermeasures addressing run off road safety are developed and verified using the identified test methods and integrated into vehicle design. Examples of systems addressing road departure avoidance aspects are Driver Alert Control and Lane Keeping Aid. Countermeasures specifically addressing occupant protection are occupant positioning by detecting run off road events and activating an electrical reversible safety belt pretensioner, as well as unique energy-absorbing functionality in the seat. Post-crash measures are enhanced by added activation of eCall in some run off road scenarios.

Optimally, avoiding the run off road is most beneficial and this study provides some initial steps illustrated by production systems. However, if run off road occurs, one priority is to reduce vertical occupant loadings when landing on the wheels after a free-flight, a rollover or when going into a ditch and impacting an embankment. This type of loading could result in thoracic-lumbar spine fractures. The design of the unique energy absorbing functionality in the seat, put into production 2015, will help provide important enhanced occupant protection.

Additionally, injury outcome is influenced by the occupant position during the event: head and arms flinging around impacting the interior, bent postures reducing the tolerances of spinal injuries, and sub-optimal occupant positioning relative to protection systems. The unique run off road detection and safety belt pretensioning early in the events, together with the seat backrest’s side supports, will assist the occupant to stay positioned during the event and help improve protection.

This study is based on a holistic approach to safety, covering the whole event from normal driving to crash care, introducing world first production technology enhancing occupant protection in these diverse and complex events. It goes beyond standardized safety evaluation of today and it provides an illustrative example on how safety systems can take action across the entire crash sequence and the interaction of different types of systems adding to the effect of addressing real world protection needs.

Links

URL: http://www-esv.nhtsa.dot.gov/Proceedings/24/files/24ESV-000424.PDF

Cited Works (5)

Year	Entry
2013	Petersson M, Svanberg B, Johansson R. Driver reaction for evaluating autonomous interventions: a test‐track method. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.653.
2001	Lorenz B, Kallieris D, Strohbeck-Kuehner P, Mattern R, Class U, Lueders M. Volunteer tests on human tolerance levels of pretension for reversible seatbelt tensioners in the pre-crash-phase phase I results: tests using a stationary vehicle. In: Proceedings of the 2001 International IRCOBI Conference on the Biomechanics of Impact. October 10-12, 2001; Isle of Man, UK.
2008	Törnvall FV, Holmqvist K, Davidsson J, Svensson M, Gugler J, Steffan H, Håland Y. Evaluation of dummy shoulder kinematics in oblique frontal collisions. In: Proceedings of the 2008 International IRCOBI Conference on the Biomechanics of Impact. September 17-19, 2008; Bern, Switzerland.195-210.
2013	Develet J-A, Carlsson A, Svensson M, Fredriksson R, Bråse D, Holcombe S. Evaluation of the biofidelity of the BioRID-II and THOR-NT anthropomorphic test devices under seatbelt pre-pretensioner loading in stationary conditions. In: Proceedings of the 9th Ohio State University Injury Biomechanics Symposium. May 19-21, 2013; Columbus, OH.
2006	Jakobsson L, Bergman T, Johansson L. Identifying thoracic and lumbar spinal injuries in car accidents. In: Proceedings of the 2006 International IRCOBI Conference on the Biomechanics of Impact. September 20-22, 2006; Madrid, Spain.61-71.

Cited By (2)

Year	Entry
2016	Jakobsson L, Björklund M, Westerlund A. Thoracolumbar spine injuries in car crashes. In: Proceedings of the 2016 International IRCOBI Conference on the Biomechanics of Injury. September 14-16, 2016; Malaga, Spain.101-112.
2020	Kullgren A, Stigson H, Axelsson A. Developments in car crash safety since the 1980s. In: Proceedings of the 2020 International IRCOBI Conference on the Biomechanics of Injury. 2020; Munich, Germany.86-99.