NHTSA has been noodling on adding an offset car crash test to its New Car Assessment Program (NCAP) for half a decade. I first discussed what is currently being referred to as the Frontal Oblique test in a 2016 “Technologue.” It involves striking a stationary test vehicle at a 15-degree angle with a moving deformable barrier traveling 56 mph. The hit is to the driver side with just 35-percent overlap to the test vehicle.
Adding new crash tests is the best way to advance overall vehicle safety and to separate the vehicle pack, once too many vehicles start earning top five-star ratings. There’s still no scheduled date for NHTSA to roll out its Frontal Oblique test, but the 2021 Acura TLX comes to market sporting an innovative new passenger airbag tailored specifically for it.
Offset car crash tests, including the 40-mph small-overlap rigid-barrier test that the Insurance Institute for Highway Safety (IIHS) rolled out in 2012, cause the vehicle to rotate more than pure frontal crashes. Adding an angle to that impact intensifies this rotation and is believed to be responsible for about a quarter of the remaining fatalities among belted occupants in airbag-equipped vehicles involved in frontal crashes.
An initial goal of the early testing was to assess whether vehicles that perform well enough in the IIHS small-overlap test to earn a Top Safety Pick+ award would require further modification to perform well in the Frontal Oblique test. No surprise, TSP+ vehicles generally outperformed vehicles that did not earn this rating (the designs of which were typically too old to have been engineered for the new test), but the results indicated that even the TSP+ vehicles would likely need some re-engineering to pass Frontal Oblique.
The big problem was brain injury risk criterion (BrIC) for the passenger dummy. The intense impact and rotation imparted by this type of offset car crash causes the passenger’s body to move sideways and head to rotate more than the driver’s. This combined motion can force the body out of the shoulder belt and cause the head to roll off the airbag and into the dashboard. Ouch.
Honda R&D, working in conjunction with safety supplier Autoliv, has come up with a new passenger airbag that more reliably engages the passenger’s head in these oblique offset crashes. Instead of providing one big pillow, it offers three separate chambers. The two side wing bags fill first, followed by a shallower center bag. A two-stage inflator makes this possible without adding size or mass. By joining the outer wings by a “sail” sheet of material that is not itself inflated, the airbag system is better able to manage the deceleration energy, slowing the head a little as it sinks into this sail, then a lot when it hits the third bag.
The airbag is designed to work the way a baseball glove captures and protects a ball that would otherwise have hit the fence, only in this case the fence might be the dashboard’s center stack. The design is said to reduce the BrIC—and hence the likelihood of brain tissue damage—by a significant 75 percent.
We expect the 2021 Acura TLX to be a top performer in this new NHTSA test whenever it finally rolls out, and you can rest assured this new airbag will propagate throughout the Honda/Acura lineup as each new product line rolls out. Best news of all: Honda R&D and Autoliv plan to freely license this potentially life- or at least brain-saving technology so that eventually all oblique-crashing passengers can come home.