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Characteristics of nearside car crashes: an integrated approach to side impact safety
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Introduction: Approximately 1.25 million people globally are killed in traffic accidents yearly. To achieve the UN Global Goal of a 50% reduction of fatal and serious injuries in 2020 a safer infrastructure, as well as new safety technologies, will be needed. Side crashes represent 20% of all serious and 25 % of fatal injuries. The overall aim of this thesis is to provide guidelines for improved side impact protection. First, by characterizing nearside crashes and injury outcome, including injuries from the farside occupant, for non-senior and senior front seat occupants. Second, to determine whether the WorldSID dummy provides opportunities for improved in-crash occupant protection. And third, by relating in-crash occupant protection to pre-crash countermeasures, to explore a holistic approach for side crashes using the integrated safety chain from safe driving to crash.

Methods: NASS/CDS data for both older and modern vehicles was used to provide exposure, incidence, and risk for fatal injury as well as detailed injury distribution and crash characteristics. The WorldSID dummy was compared to Post Mortem Human Subjects (PMHS) in impactor tests at high and low severities to demonstrate the possibilities of this tool. Crash tests were performed to evaluate WorldSID crash test dummy assessments of injuries found in the NASS/CDS data. The integrated safety chain was used to demonstrate how to evaluate occupant protection in side crashes from a larger perspective, involving infrastructure and Automated Emergency Braking.

Result: Most side crashes occur at intersections. The head, thorax, and pelvis are the most frequently injured body regions, and seniors have a higher risk for rib fractures compared to non-seniors. The WorldSID dummy response was similar to the PMHS response at the higher impact speed, but not at the lower. In conjunction with improved airbags infrastructural change, and the use of Automated Emergency Braking, can effectively reduce the number of fatalities and injured occupants in side impacts.

Conclusion: Future focus for side impact protection should be on intersection crashes, improved occupant protection for senior occupants, and protection for and from the farside occupant, reducing injury risk to the head, thorax, and pelvis. The WorldSID dummy has the ability to reproduce humanlike responses in lateral and oblique impacts. However, at a low crash severity, chest deflection could be underestimated, which must be taken into consideration when evaluating, for example, pre-crash inflated side airbags. Analyzing nearside crashes using the integrated safety chain shows that speed management by means of roundabouts is an efficient countermeasure reducing the number of injurious crashes, as well as reducing variations in crash severity. In combination with an Automated Emergency Braking a large part of side crashes could be avoided or crash severity mitigated. Rather than developing structures and airbags for high-speed crashes, it is important to consider alternative countermeasures. Hence the need for an integrated approach to side impacts.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2016. , 58 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1855
Keyword [en]
side impact, WorldSID, thorax, injuries, side airbag
Keyword [sv]
sidokollision, WorldSID, thorax, injuries, side airbag
National Category
Surgery
Research subject
biomechanics; Epidemiology
Identifiers
URN: urn:nbn:se:umu:diva-126985ISBN: 978-91-7601-587-2OAI: oai:DiVA.org:umu-126985DiVA: diva2:1039698
Public defence
2016-11-11, NUS 1D - Tandläkarhögskolan, Hörsal D, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2016-10-25 Created: 2016-10-25 Last updated: 2016-11-04Bibliographically approved
List of papers
1. Real-life fatal outcome in car-to-car near-side impacts--implications for improved protection considering age and crash severity.
Open this publication in new window or tab >>Real-life fatal outcome in car-to-car near-side impacts--implications for improved protection considering age and crash severity.
2009 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 10, no 2Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: Recent studies have shown that current side airbags, protecting head and chest, are saving lives in near-side impacts (Kahane 2007; McCartt and Kyrychenko 2007). The aim of this study was to analyze NASS/CDS real-life data on fatal trauma in near-side car-to-car crashes, stratified by age into non-senior and senior occupants. Furthermore, a hypothetical model explaining side airbag effectiveness as a function of lateral delta-v was presented. The model together with the field data was then used to demonstrate further enhancement of side airbag restraint performance.

METHOD: Weighted NASS/CDS data from 1994 to 2006 for front seat occupants in near-side car-to-car impacts was used to calculate the exposure, incidence, and risk of fatal trauma with respect to lateral delta-v. The dataset was also divided into non-senior (10-59 years) and senior (age > or = 60 years) occupants. The hypothetical model was created to adjust the NASS/CDS data to represent a car fleet fully equipped with current side airbag protection. The model was then used to evaluate the increase in effectiveness of improved side airbag protection achieved by increasing the lateral delta-v in the range where the airbag have most mitigating effect, increasing the airbag protection level within the delta-v range currently tested, and a combination of the two approaches.

RESULTS: From the NASS/CDS data, the median delta-v for fatal injury was 37 km/h for the total sample. When stratified with respect to age, the median delta-v for fatal injury was 41 km/h for non-seniors and 28 km/h for senior occupants. The exposures for both age groups were similar. However, the fatal incidence showed a difference in delta-v range between non-senior and senior occupants. Applying the airbag model increased the median delta-v to 40 km/h for the total sample and 47 and 30 km/h for non-seniors and seniors, respectively.

CONCLUSIONS: Current side airbag systems offer very good protection for non-senior occupants up to delta-v 40 km/h. Though still high, the protection for senior occupants is lower. To enhance side airbag protection, the side airbag performance should be maximized where the fatal incidence is high. Therefore, to further reduce non-senior fatalities, the test speed should be increased. To further reduce senior fatalities, the protection level within severities currently tested should be increased. A combination of the two approaches would result in about a 40 percent increase of the side airbag effectiveness.

Keyword
side impact, WorldSID, thorax, injuries, side airbag, sidokollision, WorldSID, thorax, injuries, side airbag
National Category
Environmental Health and Occupational Health
Identifiers
urn:nbn:se:umu:diva-127276 (URN)10.1080/15389580802594127 (DOI)000264847400013 ()19333834 (PubMedID)
Available from: 2016-11-04 Created: 2016-11-04 Last updated: 2016-11-04Bibliographically approved
2. Census Study of Real-Life Near-Side Crashes with Modern Side Airbag-Equipped Vehicles in the United States
Open this publication in new window or tab >>Census Study of Real-Life Near-Side Crashes with Modern Side Airbag-Equipped Vehicles in the United States
2015 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 16, no Supplement 1, S117-S124 p.Article in journal (Refereed) Published
Abstract [en]

Objective: This study aimed to investigate the crash characteristics, injury distribution, and injury mechanisms for Maximum Abbreviated Injury Score (MAIS) 2+ injured belted, near-side occupants in airbag-equipped modern vehicles. Furthermore, differences in injury distribution for senior occupants compared to non-senior occupants was investigated, as well as whether the near-side occupant injury risk to the head and thorax increases or decreases with a neighboring occupant. Method: National Automotive Sampling System's Crashworthiness Data System (NASS-CDS) data from 2000 to 2012 were searched for all side impacts (GAD L&R, all principal direction of force) for belted occupants in modern vehicles (model year > 1999). Rollovers were excluded, and only front seat occupants over the age of 10 were included. Twelve thousand three hundred fifty-four MAIS 2+ injured occupants seated adjacent to the intruding structure (near-side) and protected by at least one deployed side airbag were studied. To evaluate the injury risk influenced by the neighboring occupant, odds ratio with an induced exposure approach was used. Result: The most typical crash occurred either at an intersection or in a left turn where the striking vehicle impacted the target vehicle at a 60 to 70 degrees angle, resulting in a moderate change of velocity (delta-V) and intrusion at the B-pillar. The head, thorax, and pelvis were the most frequent body regions with rib fracture the most frequent specific injury. A majority of the head injuries included brain injuries without skull fracture, and non-senior rather than senior occupants had a higher frequency of head injuries on the whole. In approximately 50% of the cases there was a neighboring occupant influencing injury outcome. Conclusion: Compared to non-senior occupants, the senior occupants sustained a considerably higher rate of thoracic and pelvis injuries, which should be addressed by improved thorax side airbag protection. The influence on near-side occupant injury risk by the neighboring occupant should also be further evaluated. Furthermore, side airbag performance and injury assessments in intersection crashes, especially those involving senior occupants in lower severities, should be further investigated and side impact dummy biofidelity and injury criteria must be determined for these crash scenarios.

Keyword
occupant-to-occupant interaction, senior occupants, injury mechanisms, in-depth study, side impact
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-106503 (URN)10.1080/15389588.2015.1022895 (DOI)000355404600016 ()26027963 (PubMedID)
Available from: 2015-07-16 Created: 2015-07-14 Last updated: 2016-10-25Bibliographically approved
3. Response of the Worldwide Side Impact Dummy (WorldSID) to Localized Constant-Speed Impacts.
Open this publication in new window or tab >>Response of the Worldwide Side Impact Dummy (WorldSID) to Localized Constant-Speed Impacts.
Show others...
2011 (English)In: Annals of advances in automotive medicine. Association for the Advancement of Automotive Medicine. Scientific Conference, ISSN 1943-2461, Vol. 55, 231-241 p.Article in journal (Refereed) Published
Abstract [en]

The objective of this study was to evaluate WorldSID constant-speed shoulder and thorax impact responses in terms of impact force, external and internal deflection (1D and 2D IR-Tracc response) for two velocities (1 m/s and 3 m/s), at three impact levels (shoulder, upper thorax and mid thorax) in three impact directions (lateral, +15° posterolateral, -15° anteraolateral). In addition, the impact force and external deflection were compared to previously published cadaver data. Each impact condition was repeated twice. A total of 42 tests were performed. The WorldSID's lowest peak impact force and external deflection were found for impact at shoulder level regardless of impact direction. Maximum force and deflection were found for impact at mid thorax. Comparison between WorldSID and PMHS showed similar external chest deflections for impacts at 3 m/s. The peak impact force response with respect to impact level was found to be reversed for the WorldSID compared to the PMHS, for which shoulder impact resulted in the highest peak force. External time history responses for the WorldSID compared to the one PMHS impacted at 1 m/s in lateral impact direction showed a significant difference in both timing and magnitude. External deflections at upper and mid thorax were approximately twice as high as the internal 1D deflection measured by the IR-Tracc. However, taking into account the rotation of the rib, the calculated 2D deflection response at the posterior impact direction was closer to the external deflection, and thus also to the PMHS deflection response at 3 m/s. These findings emphasize the need of 2D deflection measurement.

National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-127277 (URN)22105399 (PubMedID)
Available from: 2016-11-04 Created: 2016-11-04 Last updated: 2016-11-04Bibliographically approved
4. Rate dependent spine motion and chest deflection differences between WorldSID and PMHS under localized constant-speed impacts
Open this publication in new window or tab >>Rate dependent spine motion and chest deflection differences between WorldSID and PMHS under localized constant-speed impacts
(English)Article in journal (Refereed) Submitted
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-127279 (URN)
Available from: 2016-11-04 Created: 2016-11-04 Last updated: 2016-11-04
5. Assessment of Bilateral Thoracic Loading on the Near-Side Occupant Due to Occupant-to-Occupant Interaction in Vehicle Crash Tests
Open this publication in new window or tab >>Assessment of Bilateral Thoracic Loading on the Near-Side Occupant Due to Occupant-to-Occupant Interaction in Vehicle Crash Tests
2015 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 16, no Supplement 2, S217-S223 p.Article in journal (Refereed) Published
Abstract [en]

Objective: This study aims, by means of the WorldSID 50th percentile male, to evaluate thoracic loading and injury risk to the near-side occupant due to occupant-to-occupant interaction in combination with loading from an intruding structure.Method: Nine vehicle crash tests were performed with a 50th percentile WorldSID male dummy in the near-side (adjacent to the intruding structure) seat and a THOR or ES2 dummy in the far-side (opposite the intruding structure) seat. The near-side seated WorldSID was equipped with 6 + 6 IR-Traccs (LH and RH) in the thorax/abdomen enabling measurement of bilateral deflection. To differentiate deflection caused by the intrusion, and the deflection caused by the neighboring occupant, time history curves were analyzed. The crash tests were performed with different modern vehicles, equipped with thorax side airbags and inflatable curtains, ranging from a compact car to a large sedan, and in different loading conditions such as car-to-car, barrier, and pole tests. Lateral delta V based on vehicle tunnel acceleration and maximum residual intrusion at occupant position were used as a measurement of crash severity to compare injury measurements.Result: In the 9 vehicle crash tests, thoracic loading, induced by the intruding structure as well as from the far-side occupant, varied due to the size and structural performance of the car as well as the severity of the crash. Peak deflection on the thoracic outboard side occurred during the first 50ms of the event. Between 70 to 150ms loading induced by the neighboring occupant occurred and resulted in an inboard-side peak deflection and viscous criterion. In the tests where the target vehicle lateral delta V was below 30km/h and intrusion less than 200mm, deflections were low on both the outboard (20-40mm) and inboard side (10-15mm). At higher crash severities, delta V 35km/h and above as well as intrusions larger than 350mm, the inboard deflections (caused by interaction to the far-side occupant) were of the same magnitude or even higher (30-70mm) than the outboard deflections (30-50mm).Conclusion: A WorldSID 50th percentile male equipped with bilateral IR-Traccs can detect loading to the thorax from a neighboring occupant making injury risk assessment feasible for this type of loading. At crash severities resulting in a delta V above 35km/h and intrusions larger than 350mm, both the inboard deflection and VC resulted in high risks of Abbreviated Injury Scale (AIS) 3+ injury, especially for a senior occupant.

Keyword
side impact, crash test, injury mechanisms, occupant-to-occupant interaction, WorldSID
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-110997 (URN)10.1080/15389588.2015.1061665 (DOI)000362330800030 ()26436235 (PubMedID)
Available from: 2015-11-17 Created: 2015-11-02 Last updated: 2016-10-25Bibliographically approved

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