Pedestrians are at increased risk of serious injury or death if they are struck by an SUV or pickup because of the vehicles’ high hood heights.

But research being conducted by the Collaborative Safety Research Center or CSRC, operated by Toyota Motor Co., and the University of Virginia, aims to provide information that could lead to future vehicle design to mitigate that risk.

A key element of this research is through the use of virtual human body models in conjunction with physical crash test dummies, the organizations said during a media briefing this week at the Toyota Research and Development Headquarters in Saline, Michigan.

“We’re seeing as industry explosion in virtual testing, virtual data to help assess safety of vehicles,” said Jason Hallman, CSRC senior manager.

Specifically the virtual human body model software is called Total Human Model for Safety, or THUMS.

Created by Toyota in 2000, THUMS is now in its seventh version and has been available to the industry since 2022, according to Hallman.

Essentially, THUMS can be programmed to simulate any human body type or size, in various sitting and driving positions in endless situations.

“The value of the human body model is not just that it can predict injury, but it also helps explain the motion leading to that outcome,” said Zhaonon Sun, principal scientist, CSRC. “Different geometries can create different pedestrian kinematics, so existing standard tests appropriately prioritize key injured body area regions as the head and the lower extremity, but the human body models can enable torso and spine behavior, the full body injury analysis, and provide opportunities for future research.”

The research team analyzed profiles of 400 trucks and SUVs, pulling front end geometries from images of the actual vehicles collected by the Insurance Institute for Highway Safety, according to Sun.

They then used a technique called principal component analysis to identify what are the dominant dimensions to provide what Sun called data-driven geometry descriptors, and how to understand how they differ from vehicle to vehicle, manufacturer to manufacturer, style to style.

The team came up with seven separate “geometries seen in the graphic below.

From there, it took what Sun termed a “public” pickup truck and created about 100 variants of it using the seven geometries running it through different simulated scenarios that also included speed of impact, noting different results depending on the variables.

“ That means different geometries can produce different sequences of lower extreme contact, upper body motion, neck loading, and head impact location,” said Sun. “This is important because this shows that why a single simplified view of the event is not always enough. The value of the human body model is not just that it can predict injury, but it also helps explain the motion leading to that outcome.”

Indeed, since 2011 the CSRC and the University of Virginia have run a number of studies using THUMS to investigate the effects of various crash situations, including risks when occupants are in what was termed “relaxed” seating positions, especially during automated driving periods.

The team found when it simulated the reclined seating position it revealed additional research was necessary looking at lap belt interactions with the pelvis, the torso in general and the lumbar spine, explained Jason R. Kerrigan, commonwealth professor mechanical and aerospace engineering, director center for applied biomechanics at the University of Virginia.

“So we first set out to study lap belt interactions and frontal crashes with occupants. When we did, we found that belt interaction was affected by, and really sensitive, to the subcutaneous adipose tissues surrounding the pelvis. This S A T is more commonly known as fat,” said Kerrigan.

That finding led to more than 900 experiments and helped to inform future THUMS iterations, according to Kerrigan.

Additional research using THUMS included lumbar spine compression during crashes and the discovery that females suffered more ankle injuries than males during some collisions.

Don’t blame the difference in footwear worn by the men and women, but rather a difference tolerance.

“We did find that the female tibia does generally fracture with less force than males,” Kerrigan explained.

Despite the value of simulated human body models such as THUMS, physical crash test dummies representing entire bodies or body parts remain valuable resources as they become more sophisticated and customizable.

That fact was evident as reporters were given a tour along with several demonstrations in Toyota’s safety test laboratories

containing an array of dummies representing full human bodies and body parts.

The CSRC was created in 2011 by former Toyota Motor Corporation president Akio Toyoda, with the goal of providing creative solutions to improve safety for all road users, including vehicle occupants, bicyclists, as well as pedestrians, according to Jeff Markarewicz, group vice president technical research and resources.

The organization has invested nearly $115 million since its founding on more than 120 safety-related projects working with leading universities, agencies and safety organizations across North America, publicly sharing almost all of its findings, Markarewicz said, explaining, “That openness is central to our mission, because safe mobility is not something that any one company can achieve alone,” he said.

The CSRC this week announced 10 new projects that include the effects of driver behavior, interaction with advance driver assistance alerts, speed and vehicle-to-network safety benefits.

Many of those projects will include the use of simulations via THUMS, all sharing a key intent.

“When we talk about the output that we're creating, it's not just academic papers, although those are helpful tools to bring about societal change,” declared Hallman. “What we’re really talking is about design standards or policy guidance or ways that we can standardize the assessment of the safety of vehicles.”