Grunt: The Curious Science of Humans at War

2. BOOM BOX Automotive Safety for People Who Drive On Bombs

AS SOMETIMES HAPPENS IN rural America, someone has shot up a road sign. The sign—a right-turn arrow on a yellow background—stands on a paved lane along the edge of Chesapeake Bay. Given the gape of the hole and the fact that the road traverses Aberdeen Proving Ground, there’s a good chance it wasn’t made by a bullet. A proving ground is a spread of high-security acreage set aside for testing weapons and the vehicles meant to withstand them. In the words of the next sign up the road: Extreme Noise Area.

I’m headed for Aberdeen’s Building 336, where combat vehicles come to be up-armored—as the military likes to up-say it—against the latest threats. Mark Roman, my host this morning, oversees the Stryker “family” of armored combat vehicles. He’ll be using them for an impromptu tutorial in personnel vulnerability: the art and science of keeping people safe in a vehicle that other people are trying to blow up.

My extremely uneducated guess is that some sort of shaped charge hit that sign. A shaped charge is an explosive double whammy used for breaching the hulls of vehicles and harming the people inside them. The first blast propels the murderous package to its target. On arrival, the impact detonates a wad of explosives packed inside. The blast slams a metal disc positioned in front of the explosives. Combined with the weapon’s contour, the energy of the blast shapes the metal into an extremely fast, close-range projectile that can punch through the hull of an armored vehicle with little trouble. RPGs (rocket-propelled grenades) are the ones most people have heard of, though there are ever bigger, deadlier iterations. Defense Industries of Iran is said to have one that can push through 14 inches of steel. Shooting a traffic sign with a shaped charge is like using a leather punch on a Kleenex.

By and large, an army shows up to a war with the gear it has on hand from the last one. The Marines arrived in Iraq with Humvees. “Some of the older ones had canvas doors,” says Mark, who was one of those Marines. His hair has since gone silver, but he’s retained the ready, let’s-do-this physicality that the Marine Corps seems to impart. When I asked a question about a new blast-deflecting chassis, he grabbed some wheeled mechanics’ boards and we rolled beneath a Stryker and finished the conversation on our backs.

Early on in Iraq, the Army tried plating vehicles with MEXAS armor panels, which work well against heavy machine-gun fire. “We were like, crap,” Mark recalls. “This does not stop an RPG.” You might as well have armored your vehicle with right-turn signs. Another thought was to add tiles of reactive armor, a sort of exploding Pop-Tart affair. When an RPG hits it, the filling explodes. This outward-directed blast serves to negate the blast of the RPG—and any passing pedestrian. Given that much of the fighting during the first Iraq conflict took place in urban areas—and was ostensibly an effort to “win hearts and minds” among the populace—reactive armor would have been a poor choice.

Besides, something cheaper and simpler had been found to work. Mark rolls out from under and leads the way to another Stryker, this one in a hoopskirt of heavy-duty steel grating called slat armor. The nose of an incoming RPG gets pinched between two slats, which duds it. It’s like squeezing your nose to stop a sneeze: It either prevents the explosion from happening or blocks the expulsion of nasty stuff. Either way, it proved effective. Strykers would lumber back to base like up-armored hedgehogs, bristling with RPGs. Slat armor worked so well that Iraqi insurgents largely gave up on RPGs.

And switched to making bombs. Early on in the Iraq war, improvised explosive devices were hidden on the sides of roads. Since these IED blasts hit vehicles broadside, the Army responded by flanking them with armor plates and replacing windows with “Pope glass”—two-inch thick transparent armor of the type that keeps His Holiness whole on his own tours of duty. Better, but it left the machine-gun turret exposed. Platoons tried piling sandbags up there, but they’d burst apart and literally sandblast the gunner. More ballistic shielding was added.

And thus more weight. All the added armor had Humvee engines screaming and straining on the uphills, and brakes burning out on the downs. Safety modifications on the Strykers added 10,000-plus pounds—far more than the vehicle was built to handle. You can beef up the suspension and tires, replace the engine—all of which was done—but you’ve still got problems. Past a certain tonnage, an armored vehicle begins to Godzilla the landscape. It breaks up asphalt, collapses levees. Exceeds the cargo capacity of the planes that deliver it. For every piece of armor and reinforcement, people like Mark would be called on to ditch something of similar weight. And the Stryker was never a lushly appointed vehicle. There is no onboard toilet. (There are empty Gatorade bottles.) The early ones didn’t even have air-conditioning. I tell Mark I’m glad to see some cup holders were left in place. I recognize the brief, polite silence that follows. It’s Mark Roman rendered mute by the fullness of my ignorance. They’re rifle holders.

Fast-forward to Afghanistan: land of the hundred-pound IED. To get around the up-armoring, insurgents came at vehicles from below, burying the explosives in the middle of the road rather than on the sides of it. As on most trucks, the chassis on US combat vehicles at that time were flat. Where newer generations of vehicles have V-shaped or double-V-shaped chassis to deflect the energy unleashed in a blast, the flat ones took it head-on. And because the seats were bolted to the passenger compartment floor, the energy would transmit directly to passengers’ feet, spines, and pelvises. Smacked them bad.

Newer vehicles have higher clearance. The force of a blast diminishes rapidly as it radiates outward. The energy at one or two feet is still so condensed that it can act like a solid projectile and break through vehicle floors. Once the integrity of the hull is breached, any loose piece of vehicle or gear becomes a projectile. Soldiers and Marines would pile sandbags on the floors of Humvees for the same reason aviators used to sit on their body armor instead of wearing it. Because death came up from below.

The underbody blast scenario was dire enough that US Central Command rolled out the procedural big guns: They issued a JUON (say, joo-on): a Joint Urgent Operational Need Statement. The statement surely ran longer than fifteen words, but the gist was this: Get us some combat vehicles that can drive over bombs and keep everyone inside alive. Nine vendors submitted prototypes for what would come to be known as MRAPs (say, em-wraps): mine-resistant, ambush-protected. But without fielding them first, how do you know which one is safest—and precisely how safe it is? You hire a “personnel vulnerability analyst.”

The Army Research Laboratory snapped up Nicole Brockhoff, premed at Johns Hopkins, with a graduate degree in biodefense. The youngest person to win the Secretary of Defense Meritorious Civilian Service Award. Bench presses 190. She’s come down from her office in the Pentagon to attend to some things, and agreed to make me one of them. Whenever Mark takes over the explaining, Brockhoff drops back and takes out her phone. She does not seem rude, just grindingly busy and determined to stay on top of her day. I see her come and go in my peripheral vision, pacing, answering email. She gives the impression of someone for whom idleness is almost physically unbearable. She is gorgeous, articulate, fast-moving, powerful. Lesser humans left blinking in her wake.

Brockhoff offers to show me another anti-IED modification: the energy attenuating seat. We climb inside the passenger compartment of a Stryker infantry carrier, which does not have a door but rather a drop-down ramp, like a circus boxcar. The first good thing about these new seats is that they are no longer bolted to the floor. Second, they ride on special shock-absorbing pistons. What’s special are the collapsible, replaceable metal inserts that slow the seat’s downstroke and keep it from bottoming out. The catch is that in order for passengers to protect their feet and lower legs, they need to keep them off the floor. The footrests on the base of each seat are for the person sitting directly across. Meaning that one soldier has to straddle the other’s knees for hours at a time. Mark, who has joined us, adds that having the knees up like that tends to make the butt go numb. “Like when you’re reading on the toilet too long. And you get toilet palsy.”

The last two words hover, finding nowhere to touch down. “Man thing,” Brockhoff decides.

On a long drive, fighters’ feet surely stray from the safety of the footrests. But their commanders likely know which parts of the route are riskiest and can give a heads-up.

Speaking of heads and up, I ask about airbags on the ceilings, to prevent brain injury. Unfortunately, automotive airbags don’t respond quickly enough to get the jump on a blast. Early on in her tenure at the Pentagon, Brockhoff found herself talking to a general about the challenges of high-speed energy mitigation. He suggested she talk to NASCAR.

“I said, ‘With all due respect, General….’” The bottom of a personnel carrier is traveling many, many times faster than a NASCAR race car. And unleashing a force of many times greater magnitude. Besides, NASCAR’s approach won’t work for combat vehicles. Race car drivers are packed in their seats like mail-order stemware. Heads are braced and supported, so necks don’t break and brains don’t ricochet against skulls. Danica Patrick can’t even look out the driver-side window and wink at the pit crew. That’s no good for combat vehicles. Drivers and gunners need to be scanning in all directions, looking out for suspicious elements: piles of trash or dead goats that might be hiding bombs, people holding cell phones that might be wireless detonators, children with their fingers in their ears.

At the same time that the Army was working to make existing vehicles safer, they were scrambling to evaluate the new MRAPs. When Brockhoff arrived, her colleagues were using the crash test dummy that the auto industry uses: the Hybrid III. First, because that’s what there is. And second, because it makes some sense. Both a car crash and an underbody blast cause blunt force trauma: the sorts of injuries you get from slamming into pieces of a vehicle’s interior. (As opposed to injuries caused by a blast pressure wave passing through you—rupturing organs and eardrums and the like—which a vehicle largely protects against.)

Here’s the problem: automotive crash test dummies were designed for measuring force mainly along two axes—front to back (for head-on impact), and side to side (for “T-bone” crashes). With a blast coming up from below, the axis of impact runs vertically through the body: heels to head. “This doesn’t,” Brockhoff told her colleagues gently, “seem like it’s going to be sufficient moving forward.” To make the point, a Hybrid III was filmed alongside a cadaver in a controlled blast. It is clear, from the slow-motion footage, that this dummy wasn’t built for this. It’s like watching an elderly, arthritic man try to follow along in a Zumba class. Compared with the flailing arms of the cadaver, the dummy’s barely move. When the real head comes down, the dummy’s is coming up. Its thighs rise a third as high off the seat as the cadaver’s, and its ankles barely flex.

The Hybrid III captures the basic pattern of injury—feet, lower legs, spine—but it doesn’t provide the level of detail Brockhoff’s team needed. “We were missing a lot of nuance about the severity of the injury. We needed to know, at what point do you go from a treatable injury that’s recoverable to something life-altering and incapacitating and potentially fatal? We need to be able to make those distinctions when we’re testing these trucks. And we can’t right now.”

So the Army is building a dummy of its own. WIAMan—the Warrior Injury Assessment Manikin—will be specifically tailored for underbody explosions. The project employs about a hundred people (most of whom, as far as I’ve been able to determine, have never watched Jackass and thus had no knowledge of the dwarf cast member Wee Man).

WIAMan is starting the way the automotive crash test dummy people started: with cadavers and bioengineers and controlled blasts of varying magnitude, followed by autopsies to document the injuries. Before they could start any of that, they had to build a blast rig, something robust enough to withstand an explosion directly below it. The tower, as it is conversationally known, stands in a meadow near what the mapmakers call Bear Point and the Aberdeen Explosive Effects Branch calls Experimental Facility 13. I am headed over to EF13 after lunch. The cadavers are there already, sitting in seats on the tower platform. They arrived a day ago from bioengineering labs at three universities. Some made the trip in a modified horse trailer, disappointing the children in passing cars craning their necks for a glimpse of tail or rump.

EF13 IS lovely this time of year. A late October sun softens the chill and highlights the white butterflies that flit around the bioengineers as they work. The clearing is edged by oaks, changing their outfits before dropping them to the floor. The cadavers too, wear fall colors, one in an orange Lycra bodysuit[11] and one in yellow. For now, they sit slumped in their seats, chins on their chests, like dozing subway commuters.[12] Because the setup takes two days, the dead men spent the night in the meadow. A portable weather shelter was erected to protect the electronics, and a pair of guards took turns watching from a truck parked nearby. Bear Point may not have bears anymore, but it does have coyotes, and neither death nor Lycra dampens a coyote’s enthusiasm for meat.

Under the platform is a small plot of simulated Middle East: engineered soil that has been heated and moistened as per protocol. Consistency and repeatability being key elements of the work. At around 2:30 p.m., a pickup truck will arrive with a few pounds of the explosive C-4, which everyone here has been referring to as “the threat.” Around 2:45, the bioengineers and investigators and hangers-on like me will be escorted to a nearby bunker while the threat is buried in the special dirt and a detonating wire is attached. Then the wood staircase to the tower platform will be pulled away (so the carpenters don’t have to keep rebuilding it), and an alarm will sound three times. After which the threat becomes the event. The Tower, the Threat, the Event. It’s like a tarot deck out here.

It’s just past noon now. The cadavers are having their connectivity rechecked after the long drive in. Data will be gathered from sensors mounted on their bones and then transmitted along wires laid down along the insides of their limbs and spines—a sort of man-made nervous system. As with the real deal, the nerves lead to a brain, in this case the WIAMan Data Acquisition System. A bundle of wires exit at the back of each specimen’s neck and feed into the system.

After the blast, the cadavers will be autopsied and the injuries documented. This is the information that will allow vehicle evaluators to interpret the g-forces and strains and accelerations that WIAMan’s sensors will register. Because of the cadavers’ contributions, WIAMan will be able to predict what kind and what degree of injury these different magnitudes of force would be likely to cause in an actual explosion. WIAMan won’t be done until 2021, but in the meantime, the cadaver injury data can be used to create a transfer function, a sort of auto-translate program for the Hybrid III.

By now the cadavers have been coaxed into a straight-backed dinner-table posture, some duct tape keeping them from slumping. (In coming months, data will be gathered for more realistic positions—legs stretched out in front or angled back under the seat.) A bioengineer holds one of the heads in his hands, like a man in a movie preparing to kiss his co-star. Another strings thin wires to hold the head in that eyes-right position, though not so firmly that it interferes with its movements, which will be captured on video cameras set up in bunkers on all four sides. There’s a protocol for everything: the angle of the cadavers’ knees, the position of their hands on their thighs, the newtons of force with which their boots are laced.

The bucolic calm of the setting belies the pressure everyone’s under to get the bodies prepped on schedule. A butterfly lands, unnoticed, on a bioengineer’s shoulder. Jays converse, or seem to, with the scratchy calls of duct tape being pulled from the roll. The hover and fuss of the scientists exaggerates the abiding stillness of the bodies. They’re like anchormen sitting for their makeup. How nice for them to be outdoors on this fine, crisp autumn day, I find myself thinking. How nice to be in the company of people who appreciate what they’ve agreed to do, this strange job that only they, as dead people, are qualified to do. To feel no pain, to accept broken bones without care or consequence, is a kind of superpower. The form-fitting Lycra costumes, it occurs to me, are utterly appropriate.

Not everyone feels the way I do. In 2007, someone at the Pentagon complained to the Secretary of the Army about a preliminary WIAMan test. “I’ll never forget,” says Randy Coates, WIAMan’s project director until his retirement in 2015. “It was a Wednesday evening, about seven o’clock. I got a call from a colonel over at Aberdeen, where we were going to run the test. He says, ‘The Secretary of the Army has shut down the test.’ We had three cadavers and a team of people who’d been working on them around the clock for days.” As Brockhoff recalls it, “Someone felt their personal beliefs had been affronted.” Her boss went to the Secretary and tried to explain: You can’t build a human surrogate without understanding how the human responds. And then he got mad. To shut down the project at the last moment like that would be not only an extravagant waste of money but a waste of the donors’ bodies. Sometime on Friday, the last possible day before decomposition would have invalidated the results, the test was cleared to go forward—surely the first cadaveric research venture with multiple two- and three-star generals in attendance.

Jason Tice, who oversees WIAMan live-fire testing, pointed out that the sudden, intense scrutiny may have had a silver lining. “It’s been informing leadership about the risks they’re subjecting soldiers to.” In other words, my words, maybe they’ll worry a little less about the dead and a little more about the living.

The downside to the Pentagonal hullabaloo is a newly bloated approval process. The protocol for research involving cadavers has to be approved by the head of the Army Research Laboratory and by ARL’s overseeing organization, the Research, Development and Engineering Command. From there it goes to the commanding general of the Army Medical Research and Materiel Command, which in turn passes it on to the Surgeon General of the Army, who sends it to Congress. Who have two weeks to respond. And if no one along the way takes issue, then and only then can the work begin. The whole process can take as much as six months.

The other fallout is a newly drafted “sensitive use” policy. Potential body donors are required to have given specific consent for research or testing that may involve, as the document lays it out, “impacts, blasts, ballistics testing, crash testing and other destructive forces.”

Who would sign such a thing? Plenty of people. Sometimes, Coates says, it’s people who like the idea of doing something to help keep military personnel safe. It’s a way of serving your country without actually enlisting. I can imagine there are people who, while drawn to the nobility of risking life and limb for a greater cause, would prefer to do so while already dead. Mostly, I’m guessing, it’s the same sorts of people who donate their remains for any other worthy endeavor that relies on the contributions of the insensate. If you’re fine with a medical student dissecting every inch of you to learn anatomy, or with a surgeon practicing a new procedure or trying out a new device on you, then you are probably fine riding the blast rig. I won’t be needing it, is the typical donor attitude toward his or her remains. Do what you have to do to make good from it.

IN WORLD War II they called it deck-slap. Explosions from underwater mines and torpedoes would propel a ship’s decks upward, smashing sailors’ heel bones. Like “combat fatigue” for post-traumatic stress disorder, it was a cavalier toss-off of a name for what would often turn out to be a life-altering condition. The calcaneus (the heel) is tough to break, tougher still to repair. By one early paper’s count, eighty-four different approaches had been tried and discussed in medical journals. Dressings of lint and cottage cheese. “Benign neglect.” “Mallet strikes to break up fracture fragments” followed by “manual molding” to recreate a heel-like shape. Few statistics from the era exist, but one paper cites an amputation rate of 25 percent.

Underbody blasts have brought heels back to the attention of military surgeons. The mallets and lint have been replaced with surgery and pins, but the amputation rate for deck-slap injuries is higher than ever—45 percent, in one recent review of forty cases. Part of the problem has to do with fat, not bone. The calcaneal fat pad keeps the bone from abrading the skin on the underside of the heel. It’s an extremely dense, fibrous fat found nowhere else in the body. (There’s enough squish there to merit the cobbler’s term “breast of the heel.”) Fat pads are frequently damaged in underbody blasts, sometimes badly enough that they have to be removed. Without the padding, the pain of walking is acute. When vitamin A poisoning caused the soles of Antarctic explorer Douglas Mawson’s feet to slough off, he stuffed them in the bottom of his boots like Dr. Scholl’s cushioning insoles. It was the only way he could go on.

Can’t something be put in to replace a damaged fat pad? I spoke to orthopedic surgeon Kyle Potter, who works with these patients at Walter Reed National Military Medical Center. “You mean like a small silicone breast implant?” I wasn’t actually thinking that, but sure.

“No.” Potter pointed out that breast implants aren’t designed to stand up to the forces of heel strike. Walking pounds the calcaneus with 200 percent of a person’s body weight; running, as much as 400 percent. Rupture and leakage would likely be issues. At best, Potter said, it would feel very strange. It would feel like someone stuck a breast implant in your shoe. And who, other than Douglas Mawson, would want that?

In half an hour, some deck-slap will be broadcast live on the video monitors in the bunker. We’re all over there now, while the explosives team readies the bomb. There’s not much else in here. Some microwave ovens for warming engineered soil (“DIRT ONLY,” they are labeled). An earplug dispenser by the door. The plugs are pastel foam, shot through with sparkles. It seems like a lot of manufacturing bother just to be able to call your product Spark Plugs. A wall clock shows the wrong time. “No one can figure out the admin system for the clocks,” a man explains. “We can’t spring forward and fall back.”

We stand and stare at the video feed. A slight breeze moves the trees beyond the tower. Someone with a working timepiece begins a countdown. The explosion sounds muffled, less by earplugs than by distance. We’re a half-mile away. The cadavers appear to be thrown by the blast, but not in an action-movie way. More of a took-a-speed-bump-too-fast way. As with an automotive “crash test,” the language is more disturbing than the actual event. The cadavers in an underbody blast test are blown up, as in upward, not apart.

The event is filmed at 10,000 frames per second. Playing back the footage at 15 or 30 frames per second allows the researchers to step inside the half-second lifespan of the event. Now we can see what in real time we could not. First the boots flatten, their sides bulging noticeably. An index finger rises from where it was resting on a thigh, as though the cadaver were about to make a point. The lower legs extend and rise. The head comes down and the arms shoot out in the manner of a hurdler mid-leap. Coates reverses the footage and directs me to watch the spine. As the energy of the blast moves to the seat pan, the dead man’s pelvis rises, shortening his torso and expanding his paunch. Underbody blast can compress a seated soldier’s spine by as much as two inches. Back pain and injuries, no surprise here, are common.

Played at this speed (and in this outfit), it’s modern dance. There’s grace and beauty to the limbs’ extensions, nothing brutish or violent. In real time, though, the forces that move the limbs pass too quickly for the tissue to accommodate. Muscles strain, ligaments tear, bones may break. Imagine pulling apart a wad of Silly Putty. Pull slowly, and it will stretch across the room. Yank it fast and it snaps in two. Likewise, different types of body tissue have different strain rates. For the forces of any given blast, one type may stretch, say, a fifth of its length without tearing, while another may manage just 5 percent. WIAMan will be calibrated to reflect these differences and predict the consequences.

The long-term quality of a soldier or Marine’s life is a relatively new consideration. In the past, military decision makers have concerned themselves more with go/no-go: Do the injuries keep a soldier from completing her mission? Have we lost another pawn in the game? WIAMan will answer that question, but it will answer others, too. Is this soldier likely to have back pain for the rest of his life? Will he limp? Will his heel hurt so much that he’d rather lose the foot? The answers may or may not affect the decisions that are made, but at least they’ll be part of the equation for those inclined to do the math.

BACK IN Building 336, I ask my hosts if it would be okay to try driving a Stryker. It would not. Like an obliging parent, Mark allows me to sit in the driver’s seat and turn the steering wheel back and forth. While everything else within reach seems robustly military-grade, all toggle switches and steel, the steering wheel appears to have been salvaged from a 1990s budget rental car. (And possibly was: General Dynamics, manufacturer of the Stryker, owns Chevrolet.)

Mark ousts me from the driver’s seat so he can repark the vehicle. Brockhoff, pacing at the edge of the parking lot, has found some sort of plastic packing material. She darts over to the Stryker and stuffs it in behind the backmost tire. What follows is a noise you will find nowhere in the publications of military hearing professionals: a 40,000-pound Stryker backing up over an armload of wadded-up bubble wrap.