Since 2009, there has been a documented shift in road safety for American pedestrians. After decades of declines, pedestrian fatalities have been steadily increasing since the Great Recession. Deep down, we already knew why: it’s because the cars keep getting bigger. According to a new study by The New York Times and the Insurance Institute for Highway Safety, thousands of deaths would have been prevented over the past 16 years if cars had not grown so significantly in both height and weight.

“After analyzing federal and industry records, including never-before-examined data on vehicle dimensions, we found that the rise of large pickups and S.U.V.s is an important factor,” the Times report said.

“Our estimate is that about 200 to 400 pedestrians a year would not have died if vehicles had remained approximately the same size over the past quarter-century,” the report continued. “That represents about 10 percent of the recent increase in pedestrian deaths.”

According to the report, pedestrian deaths have not only increased by 75% since 2009, but the fatalities have been correlated with the hazards presented by the physical heft, height, and blind spots inherent to today’s big trucks and SUVs.

Why 2009? The answer lies in the confluence of several consequential events of that decade. The truck and SUV boom really started in the ’90s, and likely would have kept right on roaring through the late aughts had it not been for the financial crisis. The interruption was brief, and soaring gas prices pushed nearly-new SUVs into the secondary market even quicker than usual.

Then, in the immediate aftermath of 2008, we saw not only the introduction of a stricter emissions regimen, but the restructuring of the way vehicle fuel economy was calculated to begin with. Not long after that, Cash for Clunkers came along and erased nearly 700,000 cars from the used market entirely, forcing buyers into newer models that were ostensibly more fuel-efficient.

The Obama-era revision is now referred to as the “footprint model.” It’s a formula that classifies cars by several different factors, including physical dimensions and tire size. The EPA’s new rules basically allowed automakers to pollute more so long as they made their cars a larger at the same time, but the minutiae of the government’s regulatory framework is of less importance than its unintended consequences, including the (literal and figurative) rise of the crossover, which has since supplanted the low-slung midsize sedan as America’s favorite family car—for now, at least.

Pop quiz: You’re going to get hit by something coming at you at 50 miles per hour; given equal mass, would you rather that be a small object, or a large object?

Whap! Time’s up. What did you get hit by? If you picked small, you might be dead. If you said “large,” your odds are lower. Why? Two reasons. First, F=ma and second, P = F/A. OK, I suppose that’s really just one reason, and it’s called “physics.”

In long hand, those formulas represent two related concepts. The first is force (equals) mass (times) acceleration. In other words, the force an object hits you with scales with how much it weighs and how fast it’s moving. To skip the algebra, a heavier object moving faster hurts more. Duh, right?

The second formula says that pressure (equals) force (divided by) area. This describes how the impact of that flying object is distributed. If you make the area (A) larger, the pressure (P) gets smaller even if the weight of the object is the same. As the contact area increases, the force exerted on any given part of that contact area goes down. In other words, if you could blow a bullet up to many hundreds or thousands of times its size without changing its mass, its deadliness would decline in inverse proportion to its physical size, even if it still hit you at several hundred feet per second.

But we can’t all be Dr. Strange, so let’s put this in the context of car design. It stands to reason that the most pedestrian-friendly front-ends would be those that distribute force the most widely across an impact area. Indeed, this thinking informed several European regulations that had immediate and lasting impacts on the way cars are made. The low, angular nose vanished almost overnight in favor of an upturned form resembling the business end (if there is such a thing?) of a barge.

But as we established with my half-baked physics lesson above, that’s a good thing, right? Sure, so long as we remember the one thing that didn’t change: Mass. And in case you haven’t been paying attention for the last, oh, forever, the average mass of a new vehicle has been steadily increasing, not just because each successive generation grows and adds new tech, but because the smaller cars, which previously kept the average in check, simply don’t exist anymore.

There’s a reason that automotive shrinkflation works differently than it does elsewhere. Believe it or not, it’s actually more profitable for automakers to sell you more car for your money; they handle the “shrink” angle with deft manipulation of the options sheet (not to mention deft manipulation of customer FOMO).

The issue isn’t mass alone, but also height. Yes, spreading impact over a greater area reduces the force experienced by any given part of your body, but when that surface area rises further and further from the ground, the impact point on your body rises with it. If you’re hit below your center of mass, you’re likely to fall toward the vehicle. If you’re hit at or above that point, you’re likely to be knocked down in front of of the vehicle instead. The latter becomes less survivable due to the poor visibility offered by taller trucks and SUVs.

“We see a lot of devastating collisions even at lower speeds because the pedestrian gets punted forward,” said Shawn Harrington, whose company, Forensic Rock, conducted crash testing for the report. “Before the driver knows what’s happened, the pedestrian’s head is under the wheel.”

As enthusiasts, we’ve long accepted that weight and size bloat come with performance penalties, but decades of advances in both tire and safety system engineering have given us cars and trucks that are easy to control despite being heavier and more powerful than ever. But the numbers don’t lie; this all comes at a cost, and the debt is being paid in blood.

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