Anatol Longinow placed a diagram on an overhead projector to show a roomful of colleagues the perimeter wall he designed for the Harold Washington Social Security Center on West Madison. Longinow was speaking at a dinner meeting of structural engineers on the topic “Designing to Resist Terrorist Attacks.”

Suddenly the screen behind him wrinkled and began to collapse. James Hauck, the structural engineer who’d invited Longinow to speak, bolted out of his seat, catching the screen. Two other audience members rushed to Hauck’s side to help, and for a moment, in the laughter and chaos, it looked like the enactment of a bad joke about the number of structural engineers it takes to put up a projection screen.

Structural engineers work with architects to design buildings that can resist natural forces–wind, gravity, earthquakes. Terrorism is changing the profession. After the Oklahoma City bombing, national building codes were revised to provide new buildings with more protection from catastrophic man-made events. The buildings of the future will be “beefier,” according to Hauck, with more structural redundancies to redistribute loads should portions of these buildings go violently missing. And since 9/11, the profession has been grappling with how to fortify structures that already exist.

Longinow’s talk took place the evening before Colin Powell made a case at the United Nations for war against Iraq and four days before the Department of Homeland Security, detecting the most significant threat of terrorism since 9/11, put the country on orange alert. Leaving aside the question of whether there’s a connection between the Bush administration’s march toward war and the increasing threat of attack, we’ve all known since the twin towers collapsed that another act of terrorism on U.S. soil is likely. The 50 structural engineers who came to hear the talk might well have believed they were in a position to make the public safer.

Every month the Structural Engineers Association of Illinois hosts a dinner lecture, an event that Hauck, the organizer, refers to as a “nerd fest.” But the engineers gathered at the Wrigley Building’s 410 Club looked like any other group of well-to-do professionals meeting after hours. They sipped wine and beer and talked shop.

One man stood out from the crowd. He was wearing a zip-up sweatshirt over a dress shirt and tie and drinking through a straw from a Styrofoam cup. His name tag said Robert Johnson, and within minutes of my arrival he was stuffing flyers for upcoming events into my hands and ushering me around the room to meet his colleagues. He couldn’t have been happier to see a reporter. “We refer to ourselves as the stealth profession,” he told me. “Nobody knows who we are until something goes wrong. Then it’s ‘Who did that?'”

As SEAOI’s public relations chair-man, a position he’s held since 1986, Johnson finds engineers’ invisibility a constant source of irritation. He has penned several articles for trade publications–with titles like “Hollywood, We Have a Problem”–lamenting the dearth of public recognition engineers get compared to athletes and other celebrities, whose contributions to humanity, he points out, are far more trivial.

Johnson introduced a man wearing a tie clip in the shape of a steam locomotive. The man, Chas Hague, designs railroad bridges, and before I knew it he was sketching trusses in my notebook to illustrate why the Tacoma Narrows Bridge collapsed in 1940. (“Engineers can’t talk without a pencil in their hand,” he said.)

Hague pointed out that when Frank Lloyd Wright’s Imperial Hotel remained standing after the 1923 earthquake devastated Tokyo, “everyone said that’s because Frank Lloyd Wright is a great architect.” Clearly exasperated, he continued: “It was his structural engineer!”

“William Peters,” Johnson quickly added, wanting to give credit where credit was due. (Later, Johnson realized that Peters hadn’t actually started working with Wright until after the hotel was built and that this engineer–whatever his name was–would remain, like so many others, in obscurity.)

“There’s Mr. Antenna!” Johnson suddenly said, trundling me over to meet Sherwin Asrow, who designed the antennas on the Sears Tower and is responsible for making sure the ones on the Hancock remain standing. Asrow concurred with the unsung-heroes bit. “Engineers are a very interesting group of people,” he said. “For the most part we’re in the background.”

Every year the Draper Prize–the most prestigious award you’ve never heard of–gives half a million dollars to an engineer who has made a prodigious contribution to the field. It bothers Johnson that the winners aren’t household names. At least two of them, Hague told me, have gone on to win the Nobel Prize. Johnson rattled off some past winners, engineers who designed the turbojet engine and developed the technology for communication satellites and time-release drugs.

That the work of engineers is hugely important was evident from the subject of the evening’s talk. “Most structural engineers know very little about what to do to design for a terrorist attack,” Hauck said while introducing Longinow. The presentation was “designed to take a little mystery out of that.”

A consultant with a local forensic engineering company that investigates structural failures, Longinow is a soft-spoken man with a Ukrainian accent. He emigrated to the U.S. in 1947, when he was 14. From 1964 to 1980 he worked in Chicago for the government’s civil defense agencies, studying the possible effects of nuclear weapons, calculating population survival, and identifying buildings that could be used as fallout shelters.

After Timothy McVeigh destroyed the federal building in Oklahoma City, Longinow turned his attention to vehicle bombs. He developed a course for FEMA and contributed articles to engineering journals. One he cowrote with Kim Mniszewski in 1996 seemed only slightly more comforting than the government’s blithe cold-war reminders to duck and cover: “Designing conventional, above-grade structures to significantly resist the effects of blast is generally impractical.” The article did, however, offer some tips for minimizing those effects.

Federal buildings–courthouses, for example–have long operated at high security and were assumed to need some level of blast protection, but Longinow found himself in demand in the private sector after September 11. He “hardened” the Kennedy Center for the Performing Arts in Washington, D.C., and was asked to put together a proposal for hardening a Chicago building (which he didn’t name) that houses VIPs from all over the world. (Ultimately the building owner determined the threat to the building wasn’t great enough to justify implementing the costly plan.) Around this time Longinow even got a call from the nervous owner of a high-rise condo who wanted to make his unit blast-resistant. Longinow explained to the man that the building itself had to be blast-resistant.

Citing the 1983 attack on the marine barracks in Beirut, the 1993 attack on the World Trade Center, and the bombing in Oklahoma City, Longinow told his audience he believes the most significant threat to the country is the vehicle bomb, and that the first line of defense, so to speak, is security. He encouraged his colleagues to consult with security specialists when hardening buildings. “My friends in security tell me that if your enemy perceives that a facility has more obstacles than an intruder is willing to overcome, it will not be selected for attack.”

Longinow talked about countermeasures, such as “deception.” At a military facility, for example, “you can have an entrance that looks like an entrance that is [really] a blank wall.” At a bank, you could back windows with masonry that doesn’t show from the outside.

But the most important thing, he said, is to give the building a wide perimeter. This can be done with fences, concrete-filled bollards, planters, heavy-equipment tires jutting out of the ground, and other things that can “screw up traffic.” He told us that in tests, heavy-equipment tires stopped a 3,300-pound vehicle traveling at 50 miles an hour–a comforting thought until he added, “I stole this from a Corps of Engineers manual, so I don’t know if this is true or not.”

“Could be deception,” cracked Josie Branco, one of the few women in the group.

The fertilizer-based explosive that McVeigh used was equivalent to 4,000 pounds of TNT, and when a bomb of that magnitude explodes you’d better hope you’re far away. Very far away. According to Longinow’s calculations, the pressure at 40 feet from the center of such an explosion would be 197 pounds per square inch–a figure that made someone in the audience audibly suck in his breath, while another person let out a quiet whistle.

“That’s a big damage area,” Longinow agreed.

Structural engineers in Chicago typically design for 85- to 100-mile-an-hour wind loads and think in pounds per square foot, not pounds per square inch, so Longinow did a quick calculation for the group. “If we compute the pressure in 100-mile-per-hour wind, it’s going to be approximately 63 psf, which is .43 psi,” he said. “If you want to know the distance at which [a weapon equivalent to 4,000 pounds of TNT] will give you .43 psi, it’s 1,372 feet. So you can sort of visualize, if you want your facility to be safe, you have to be approximately 1,400 feet away from the point of the explosion.”

In other words, in order not to damage a building, a bomb the size of McVeigh’s would have to be detonated a quarter mile away–about as far away as the Sears Tower is tall.

“That’s a hell of a perimeter,” someone said.

“So what are your options as an engineer?” Longinow said. With existing buildings, “the first option is take a look and see if you can extend the perimeter.” But for most buildings in downtown Chicago that’s not possible. His other suggestions had less to do with structural engineering than with architecture and interior design. “You can put offices in the interior to prevent damage from blast entering the building directly and put corridors on the outside,” he told the group. And for “fragment mitigation,” you could hang floor-to-ceiling curtains that would capture shards of glass or coat the windows with “nonfragmenting glazing.” Fastening down furniture would also minimize injuries. Everything else he mentioned seemed designed to aid the evacuation of those lucky enough to survive the blast: emergency power, first-aid equipment, communications equipment, rope, ladders, food, water.

Longinow ended his talk on a grim note: “If you don’t have the room you need to give you a big perimeter, well, then move someplace else.”

Then one man in the audience expressed what must have been on everyone’s mind: “It sounds impossible to stop a blast that’s close by with any conventional construction that I can think of.”

The engineers began searching for something–anything–that could provide a bit of optimism. Does it make sense to prioritize certain spaces? someone asked. Maybe let the blast go through a lobby?

“If the lobby’s taken away and if the columns are taken away, then the rest of the building will go too,” Longinow said.

Someone else wanted to know if there are benefits to having a facility underground. “Belowground facilities are very strong” was all Longinow would allow.

Could you redirect the blast somehow? Create a geometric shape that would deflect the wave around it? “And hit the neighbor,” Branco said, providing another bit of comic relief.

Unfortunately, Longinow said, the tendency of the blast wave is to “reconstruct itself” after it passes an obstacle–say, a berm. “So immediately in the back of the berm, you’re safe; a little further out, the shock wave reconstructs itself to the same thing it would have been had the berm not been there.”

A couple of days later, Johnson said he’d been hoping for more “nuts-and-bolts” suggestions for how to resist blast effects. The bottom line, he said, is that if someone is hell-bent on bringing down a building, “there really isn’t much you can do about it.” And the engineer who could? Well, he or she would surely be a household name.

Art accompanying story in printed newspaper (not available in this archive): photo/Cynthia Howe.