Since the 1970s, crash test dummies – mechanical surrogates of the human body – have been used to determine car safety.
The technology is used to estimate the effectiveness of seatbelts and safety features in new vehicle designs. Until now the most commonly used dummy has been based on the average male build and weight.
However, women represent about half of all drivers and are more prone to injury in like-for-like accidents. The dummy that is sometimes used as a proxy for women is a scaled-down version of the male one, roughly the size of a 12-year-old girl.
At 149cm tall (4ft 8ins) and weighing 48kg (7st 5lb), it represents the smallest 5% of women by the standards of the mid-1970s.
However, a team of Swedish engineers has finally developed the first dummy, or to use the more technical term – seat evaluation tool – designed on the body of the average woman.
Their dummy is 162cm (5ft 3ins) tall and weighs 62kg (9st 7lbs), more representative of the female population.
So why have safety regulators not asked for it before now?
‘A male decision’
“You can see that this is a bias,” said Tjark Kreuzinger, who specialises in the field for Toyota in Europe. “When all the men in the meetings decide, they tend to look to their feet and say ‘this is it’.
“I would never say that anybody does it intentionally but it’s just the mere fact that it’s typically a male decision – and that’s why we do not have [average] female dummies.”
Several times a day in a lab in the Swedish city of Linköping, road accidents are simulated and the consequences are analysed. The sensors and transducers within the dummy provide potentially lifesaving data, measuring the precise physical forces exerted on each body part in a crash event.
The team record data including velocity of impact, crushing force, bending, torque of the body and braking rates.
They are focused on seeing what happens to the biomechanics of the dummy during low-impact rear collisions.
When a woman is in a car crash she is up to three times more likely to suffer whiplash injuries in rear impacts in comparison with a man, according to US government data. Although whiplash is not usually fatal, it can lead to physical disabilities – some of which can be permanent.
It is these statistics that drive Astrid Linder, the director of traffic safety at the Swedish National Road and Transport Research Institute, who is leading the research in Linköping.
“We know from injury statistics that if we look at low severity impacts females are at higher risk.
“So, in order to ensure that you identify the seats that have the best protection for both parts of the population, we definitely need to have the part of the population at highest risk represented,” she told the BBC.
Dr Linder believes her research can help shape the way cars are specified in the future and she stresses the key differences between men and women. Females are shorter and lighter than males, on average, and they have different muscle strengths.
Because of this they physically respond differently in a car crash.
“We have differences in the shape of the torso and the centre of gravity and the outline of our hips and pelvis,” she explained.
But Dr Linder will still need regulators to enforce the use of the average female she has developed.
Currently there is no legal requirement for car safety tests for rear impact collisions to be carried out on anything other than the average man.
Although some car companies are already using them in their own safety tests they are not yet used in EU or US regulatory tests.
Engineers are starting to create more diverse dummies, including dummies that represent babies, elderly and overweight people.
The average female dummy in Linköping has a fully flexible spine, which means the team can look at what happens to the whole spine, from the head to the lower back, when a woman is injured.
US company Humanetics is the largest manufacturer of crash test dummies worldwide and is seen as the leading voice when it comes to the precision of the technology.
CEO Christopher O’Connor told the BBC he believes that safety has “advanced significantly over the last 20, 30, 40 years” but it “really hasn’t taken into account the differences between a male and a female”.
“You can’t have the same device to test a man and a woman. We’re not going to crack the injuries we are seeing today unless we put sensors there to measure those injuries.
“By measuring those injuries we can then have safer cars with safer airbags, with safer seatbelts, with safer occupant compartments that allow for different sizes.”
The UN is examining its regulations on crash testing and will determine whether they need to be changed to better protect all drivers.
If changes are made to involve a crash test dummy representing the average female, there is an expectation that women will one day be safer behind the wheel.
“My hope for the future is that the safety of vehicles will be assessed for both parts of the population,” Dr Linder said.
