Study: Higher hoods + higher speeds = more death

Yet another study from the IIHS concludes that the design of our vehicles has to change.

Me and my GMC in Detroit

Last year, I wrote about a study by the Insurance Institute for Highway Safety (IIHS), which found SUVs and pickups with high flat fronts are 45% more likely to kill. And while we have known for years that the rate of death increases with the speed of the vehicle, new research from the IIHS looks at the combination of speed and hood height. To no one’s surprise, it concludes that taller vehicles compound the risk from higher crash speeds.

“A small increase in crash speed can really ramp up the danger to a pedestrian,” IIHS President David Harkey said in a press release. “Our fondness for tall SUVs and pickups in the U.S. has intensified that effect.”

The study compared crash data from Germany, where the vehicles comply with the Euro-NCAP standard for protecting pedestrians and light trucks like the Ford Transit have a low sloping front end. Pedestrians are more likely to be seen, and when they are hit, are more likely to roll up on top rather than having to be picked out of the grille.

At slow speeds, under 20 MPH, almost everyone who is hit survives. At 60 MPH, almost everyone dies. But in between, the pickup trucks represented by the blue line are significantly more likely to cause serious injury or death.

“For serious injuries, the risk curve for the median pickup is not just shifted left compared with the median car, but is steeper as well. In other words, speed increases have a more pronounced effect when taller vehicles are involved. For example, as crash speed increases from 15 mph to 35 mph, the risk of a serious injury goes from 9% to 52% when a median-height car is involved. With a median pickup, the risk shoots up from 11% to 91%.”

There are a couple of lessons that come out of this study. The first one is that lower speed limits save lives and reduce injuries. The study authors, Samuel S. Montfort and Becky C. Mueller, write:

“Our findings suggest that lowering the speed limit to 15 mph in areas with large numbers of pedestrians would significantly improve crash outcomes. Indeed, a study of 40 European cities that implemented a similar speed limit city-wide (30 km/h, or 18.6 mph) observed a significant decrease in crashes, injuries, and fatalities following the change.”

They acknowledge that 15-mph might be a hard sell, but any reduction is going to make a difference; goijng from 30 mph to 25 mph (49 km/h to 40 km/h) cut the rate of serious injury in half.

My granddaughter and a neighbour’s truck

Then there is the issue of design. Taller vehicles are more likely to hit pedestrians than lower ones due to decreased visibility; it’s hard for the driver to see my granddaughter when there is so much between them. The A-pillars holding up the roof are beefed up to support the weight of the truck in a rollover, so the visibility while turning is significantly reduced. (See other IIHS research covered in Turning Pickup Trucks are 4 Times as Likely to Kill Pedestrians) They are then way more likely to kill or seriously injure them, in direct proportion to the height of the hood. “In sum, vehicle height significantly increased the risk of pedestrian injury overall as well as the potency of impact speed for taller vehicles.”

Yet as the study authors note, there is no regulation of design in North American and the drivers don’t care; they feel safer inside.

“There are currently no regulatory or consumer tests in the United States that incorporate the height of a vehicle's front end and its relationship with pedestrian injury risk. Unfortunately, the greater injury risk that large vehicles pose to pedestrians is an externality that is unlikely to be accounted for by purchasers of those vehicles. The data are increasingly clear that taller vehicles inflict more severe pedestrian injuries, and so special attention should be paid to developing regulatory and engineering countermeasures for these crash scenarios.”

This study looked at the deadly combination of speed and hood height, concluding that they both have to be lower. The IIHS president concludes:

“This study is a vivid illustration of how multiple factors — in this case speed and vehicle height — converge to create negative outcomes on the road,” Harkey said. “Similarly, it will take a combination of actions from different corners of the transportation world to improve pedestrian safety.”

Yes, we need local regulation of speed limits, and government regulation of vehicle design that considers people outside of the vehicle. But I have never understood why the IIHS doesn’t get more involved, or why it can’t seem to make up its mind about this issue; it concludes that big vehicles kill, yet tweets that smaller cars provide less crash protection. It was founded and funded by the insurance industry, and it has its own vehicle testing facility. It comes up with its “top safety picks” yet says “Larger, heavier vehicles generally afford more protection than smaller, lighter ones.”- without mentioning anything about pedestrian safety.

To its credit, it does do some pedestrian testing, but just for emergency braking systems, not vehicle design. They could play a bigger role here.

I traded my Miata in for an e-bike a few years ago because it was so low and small I thought someone in a pickup would drive over me at some point. These days I often feel that way in our Subaru Impreza. I have written before that car bloat is getting ridiculous and must be stopped; This new research shows that it is also deadly.

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See also other posts I have written on this subject:

A Tale of Two Trucks: Why US Pickups Need European-Style Regulations

New studies find SUVs and pickups with high flat fronts are 45% more likely to kill.- The IIHS calls for automakers to "take a hard look at the height and shape of their SUVs and pickups.” We call for regulation.

It's time for limits on truck and SUV size and weight- They take up too much space, and they kill far too many pedestrians and cyclists.