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Interaction between humans and car seats: studies of occupant seat adjustment, posture, position, and real world neck injuries in rear-end impacts
Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: The latest generation of rear-end whiplash protection systems, as found in the WHIPS Volvo and SAHR Saab, have reduced injury rates by almost 50% in comparison with the previous generation of seat/head restraint systems. Occupant behaviour, such as seated posture and seat adjustment settings, may affect the injury risk. Method: Five studies were conducted. Studie I was an injury outcome study based on insurance data. Studies II-IV investigated seat adjustment, occupant backset, and cervical retraction for drivers and occupants in different postures and positions in the car, during stationary and driving conditions. Study V compared the occupant data from studies II and III with a vehicle testing tool, the BioRID dummy, using the protocols of the ISO, RCAR, and the RCAR-IIWPG.

Results: Female drivers and passengers had a threefold increased risk for medically-impairing neck injury in rear-end impacts, compared to males. Driver position had a double risk compared with front passenger seat position. Female drivers adjusted the driver seat differently to male drivers; they sat higher and closer to the steering wheel and with more upright back support. The volunteers also adjusted their seat differently to the ISO, RCAR, and RCAR-IIWPG protocol settings; both sexes sat further away from the steering wheel, and seat back angle was more upright then in the protocols. In stationary cars, backset was highest in the rear seat position and lowest in the front passenger seat position. Males had a larger backset than females. Cervical retraction decreased and backset increased for both sexes when posture changed from self-selected posture to a slouched posture. The BioRID II dummy was found to represent 96th percentile female in stature, and a 69th percentile female in weight in the volunteer group.

Conclusions: Risks in car rear-end impacts differ by sex and seated position. This thesis indicates the need for a 50th percentile female BioRID dummy and re-evaluation of the ISO, RCAR, and RCAR-IIWPG protocols, and further development of new safety systems to protect occupants in rear-end impacts.

Place, publisher, year, edition, pages
Umeå: Kirurgisk och perioperativ vetenskap , 2008. , 39 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; ISSN 0346-6612-1163
Keyword [en]
Surgery, backset, Whiplash, rear-end impact, seated posture, seated position, bioRID
Keyword [sv]
Kirurgi
Research subject
Surgery
Identifiers
URN: urn:nbn:se:umu:diva-1636ISBN: 978-91-7264-525-7 (print)OAI: oai:DiVA.org:umu-1636DiVA: diva2:141635
Public defence
2008-05-23, Sal D, Tandläkarhögskolan 9tr, Umeå Universitet, 901 85 Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2009-05-04Bibliographically approved
List of papers
1. The risk of whiplash-induced medical impairment in rear-end impacts for males and females in driver seat compared to front passenger seat
Open this publication in new window or tab >>The risk of whiplash-induced medical impairment in rear-end impacts for males and females in driver seat compared to front passenger seat
2013 (English)In: IATSS Research, ISSN 0386-1112, Vol. 37, no 1, 8-11 p.Article in journal (Refereed) Published
Abstract [en]

The objective of this study was to study whiplash injury outcome in front-seat occupants in rear-end impacts using double paired comparison technique. The combination of gender, seated position, and outcome was analyzed. Folksam, a Swedish insurance company, has a database of whiplash injuries. A questionnaire was used to collect study data. The response rate was 81%. The inclusion criteria included medical impairment one year after the impact, as judged by medical specialists. The study included rear-end impacts between 1990 and 1999 that resulted in at least one permanent neck injury impairment; in total, 430 impacts with 860 occupants and 444 impairments. Of those suffering impairment, 302 were female and 142 male; 235 were seated in the driver's seat and 209 in the front passenger seat. Relative risk estimates for impairing whiplash injury, by gender and seated position:

1.Driver male (DM)/passenger female (PF) relative risk = 0.5 n = 218

2.Driver male (DM)/passenger male (PM) relative risk = 1.4 n = 57

3.Driver female (DF)/passenger female (PF) relative risk = 2.5 n = 102

4.Driver female (DF)/passenger male (PM) relative risk = 4.6 n = 67.

Females had a relative risk of medical impairment of 3.1 compared to men after adjustment for the average increased risk in the driver position. The driver position had a doubled relative risk compared to the front passenger position. As a conclusion it may be of value to take risk differences between male and female occupants and between driver and front passenger positions into account in future automotive car and seat construction.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Rear-end impact, Whiplash, Gender, Driver seat, Front passenger seat
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-3146 (URN)10.1016/j.iatssr.2013.04.001 (DOI)
Note

Originally mentioned in thesis as submitted to journal: Traffic injury prevention, ISSN 1538-9588.

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2017-05-29Bibliographically approved
2. Seat adjustment: capacity and repeatability among occupants in a modern car
Open this publication in new window or tab >>Seat adjustment: capacity and repeatability among occupants in a modern car
2008 (English)In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 51, no 2, 232-241 p.Article in journal (Refereed) Published
Abstract [en]

Families in the Western world have a car and several family members share the same car. In this study, 154 participants have adjusted a driver's seat three times. The primary objective was to study intrapersonal repeatability and intraclass correlation (ICC) on seat; length adjustment, backrest angle, seat front edge and seat rear edge adjustment, related to participant age, sex, stature and weight. Length adjustment has the best intrapersonal repeatability within two repetitions, 49 mm and ICC-value 0.87. Females and younger participants (age < 40 years) adjust seats generally more accurately. Females adjust the seat 41 mm more forward, 120 mm compared to men 79 mm counted from 0-starting position. Females sit with more upright seat backrests, 46 degree compared to 43 degrees for males counted from 0-starting position. Females sit higher than males in both the frontal and rear part of the seat cushion.

Place, publisher, year, edition, pages
Taylor & Francis, 2008
Keyword
car, seat, adjustment, sex, age, length
National Category
Medical Ergonomics Engineering and Technology Applied Psychology
Identifiers
urn:nbn:se:umu:diva-22162 (URN)10.1080/00140130701561793 (DOI)000253314700009 ()17896222 (PubMedID)
Available from: 2009-04-24 Created: 2009-04-24 Last updated: 2015-09-08Bibliographically approved
3. Backset and cervical retraction capacity among occupants in a modern car.
Open this publication in new window or tab >>Backset and cervical retraction capacity among occupants in a modern car.
2007 (English)In: Traffic Inj Prev, ISSN 1538-9588, Vol. 8, no 1, 87-93 p.Article in journal (Refereed) Published
Keyword
Accidents; Traffic, Adult, Automobiles, Biomechanics, Cervical Vertebrae/injuries, Female, Head, Humans, Male, Middle Aged, Protective Devices, Sex Factors, Whiplash Injuries/*physiopathology/*prevention & control
Identifiers
urn:nbn:se:umu:diva-16265 (URN)10.1080/15389580600911010 (DOI)17366340 (PubMedID)
Available from: 2008-10-07 Created: 2008-10-07 Last updated: 2009-08-11Bibliographically approved
4. Backset-stationary and during car driving.
Open this publication in new window or tab >>Backset-stationary and during car driving.
2008 (English)In: Traffic injury prevention, ISSN 1538-957X, Vol. 9, no 6, 568-573 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: The aim of the study was to measure and analyze backset, defined as the horizontal distance between the back of the occupant's head and a point located on the ventral/top aspect of the sewn rim of the head restraint, with the car stationary and during driving, in the driver's position in a modern car. METHODS: A population of 65 subjects, 35 males and 30 females, was studied in a Volvo V70 car, model year 2007. The subjects were studied in the driver's position, in a self-selected posture. Stationary backset was measured with the technique described by Jonsson et al. (2007) and backset during driving with video analysis. Descriptive data were calculated, and variability and correlation analyses were performed. A t-test was used to test differences of means. Significance level was set to 0.05. RESULTS: In comparison to stationary backset, mean backset during driving was 43 mm greater in males and 41 mm greater in females. Driving backset was 44 mm larger in males than in females. Driving backset was moderately correlated (0.37-0.43) to stature, seated height, and seat back angle in males and moderately correlated (0.44-0.52) to hip width, waist circumference, and weight in females. The overall intraclass correlation coefficient for backset during driving was 0.81 (CI: 0.75-0.86). CONCLUSIONS: These results may be of use in designing future updates of test protocols/routines for geometric backset, such as RCAR and RCAR-IIWPG.

Keyword
Whiplash; Backset; Retraction; Posture; Driving; Stationary
Research subject
Surgery
Identifiers
urn:nbn:se:umu:diva-18512 (URN)10.1080/15389580802308312 (DOI)19058104 (PubMedID)
Available from: 2009-02-12 Created: 2009-02-12 Last updated: 2010-04-14
5. BioRID II manikin and human seating position in relation to car head restraint
Open this publication in new window or tab >>BioRID II manikin and human seating position in relation to car head restraint
2008 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 13, no 5, 479-485 p.Article in journal (Refereed) Published
Abstract [en]

The objective of the study was to compare stature, weight and backset (the horizontal distance (x) between the back of the occupant's head and the front of the seam on top of the head restraint) of the Biofidelic Rear Impact Dummy (BioRID II) to the same variables on seated volunteers in a car. The following methods were used. Data were collected from 154 randomly selected Swedish individuals (78 males and 76 females). The volunteers and the BioRID II were examined in a Volvo V70 car, year model 2003, in three positions: driver (hands on steering wheel), front passenger (hands in lap) and rear passenger. The study results were as follows: the BioRID II was found to correspond approximately to a 35th-45th percentile male in stature (-2 cm), a 35th percentile male in weight (-7 kg), a 96th percentile female in stature (+11 cm) and a 69th percentile female in weight (+8 kg). The BioRID II was designed to represent a male driver. The BioRID II backset corresponded well with the average of the male drivers of its stature. Larger deviations in backset were found for other volunteer sizes and other seating positions. The average backsets were 26 mm for females and 63 mm for males in the front seat positions. The volunteers had larger backset in the driver position (60 mm) than in the front passenger position (29 mm). Smaller differences in backset were seen between the BioRID II and the volunteers in the rear passenger position. This study provides data regarding the occupant size coverage of BioRID II, and unique data regarding backset, of different occupant positions in the car; driver with hands on steering wheel, and front and rear passengers with hands in lap, for female and male in relation to the BioRID II dummy.

Place, publisher, year, edition, pages
Abingdon: Taylor & Francis, 2008
Keyword
BioRID II, stature, weight, backset, gender, position
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-3150 (URN)10.1080/13588260802120926 (DOI)000259036900002 ()
External cooperation:
Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2016-08-30Bibliographically approved

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