Road traffic collisions are a major cause of mortality and morbidity in the European Union and the U.S.; in 2009, collisions resulted in an estimated 34,500 deaths in the EU-27 and 30,862 deaths in the U.S. (Eurostat, 2011; NHTSA, 2012). Deaths are also concentrated among men. In both the EU and U.S., men are 2.6 times as likely as women to die in road collisions (DG Energy and Transport, 2009; Kposowa et al., 2009).
Multiple research projects have been undertaken with the goal of developing a finite-element model of the human body to enhance safety engineering. Consistently, models have been initially based on 50th percentile male anthropometry, with some models later expanded to include larger and smaller bodies (Yang et al., 2006). Following this pattern, the Human Model for Safety (HUMOS-1), funded under the EC Fourth Framework Programme (FP4) from 1997 to 2000, was based on the study of a single male cadaver, representing "a 50th percentile seated man" (Pajon et al., 2002).
HUMOS-2, funded under the EC Fifth Framework Programme (FP5) from 2002 to 2006, expanded data collection to include humans from the 5th, 50th, and 95th percentiles,—i.e., lighter people (mostly women) and heavier people (mostly men) (Toma et al., 2010; Acart et al., 2009a; Dupont-Kerlan et al., 2006). Biofidelic models are, however, still developed first for the 50th percentile man, from the outset excluding people who are significantly smaller or larger. One such example is the Global Human Body Models Consortium (GHMBC) model (GHMBC, 2012).
The European Union Framework Programme 7 (FP7) Tho
del (THOMO) project
aims to develop a numerical, "finite element model of the human thorax and upper extremities" (THOMO, 2012). Data-gathering procedures by THOMO and associated research teams can be sorted into two basic categories:
- A. Measurement of the thoracic skeleton (imaging of ribs, sternum, vertebrae, and cartilage) with computed tomography (CT), laser scans, and microtomography (μCT) (Mayeur et al., 2010).
- B. Biomechanical stress tests on cadaver ribcages. Dynamic test endpoints include deformation under strain and actual fractures.
Biomechanical tests are designed to simulate forces exerted on the thorax from both front- and side-impact automotive crashes. Tests cover a variety of scenarios, including drivers/passengers who are wearing 3-point seatbelts, wearing 4-point harnesses, or unbelted, in crashes with or without airbag deployment.
THOMO project measurements and biomechanical tests are performed on cadavers from France corresponding to the following percentiles of overall human body weight:
- 50th (11 male cadavers and 1 female cadaver)
- 5th (6 female cadavers)
THOMO uses scaling to model other size percentiles (THOMO, 2012).
THOMO is one of four biomechanical modeling projects under the EU's Coordination of Vehicle and Road Safety Initiatives (COVER) consortium. All COVER projects are funded under FP7 and each has a distinct focus (Lemmen et al., 2009) - see diagram:
The THOMO project is one of several Centers of Expertise for the privately funded Global Human Body Models Consortium (GHMBC), which consists of nine automobile manufacturers from EU countries, the U.S., South Korea, and Japan, as well as the U.S. National Highway Traffic Safety Administration (NHTSA) (GHBMC, 2012).
Automotive manufacturers continue to develop finite-element models for safety engineering purposes (Leonardi, 2009). One example is the Total Human Model for Safety (THUMS), a proprietary project of the Toyota Motor Corporation (Maeno et al., 2001). The initial version of THUMS was based on anthropometry of a 50th percentile U.S. man (Chawala et al., 2005; Oshita et al., 2002). Currently, engineers are expanding the model to include 5th percentile American women, 95th percentile American men, and pregnant women (Iwamoto et al., 2007).
Gendered Innovation 1: Modeling Women's and Men's Thoraxes
The THOMO project models both women's and men's thoraxes by gathering data from bodies ranging from the 5th to 50th weight percentiles (THOMO, 2012).
Studies of crash outcomes show that women drivers are approximately 47% more likely than men drivers to sustain severe injuries in automotive crashes when researchers control for factors such as height, weight, seatbelt usage, and crash intensity; that is to say, a seatbelt-wearing woman driver involved in a crash is more likely to be injured than a seatbelt-wearing man driver of identical height, weight, and age involved in an identical crash (Dipan et al., 2011; Evans, 1999). Several sex and gender factors may influence observed differences in crash outcomes:
- 1. Injury threshold: Women have a lower average injury threshold than men for some mechanisms of injury, such as whiplash, but young men have a lower velocity injury threshold than young women (Talmor et al., 2010; Stemper et al., 2004).
- 2. Design: Women may have excess risk because "effectiveness of occupant safety devices is biased toward the male occupants" (Dipan et al., 2011).
- 3. Type of vehicle driven: In the U.S., where data are available, women tend to drive cars with higher safety ratings than do men (Ryb et al., 2010).