When Vauban, Louis XIV’s chief military engineer,
first planned and constructed a network of fortifications around the
perimeter of France in the 1660s and 1670s, a new idea of the state as
an impregnable fortress was being advanced. More than three centuries
later, the fantasy of such simple geographies no longer holds sway. The
center and the periphery, the inside and the outside, now overlap in
non-linear patterns, dismantling Vauban’s dream of an invincible and
secure inside. From Cold War Berlin to current day West Bank, from the
Mexican-American “border” that cuts deep into the American South to
almost every American city shredded by class and race divisions, what
we see instead is that the border, as both psycho-geography and
reality, refuses to remain at the edge of the nation-state. The threat
of domestic terrorism, homegrown or foreign, is now the most visible
mode in which the border mentality manifests itself in the US; the bomb
is its most spectacular weapon.
In such a world, “the
building is our last line of defense,” as Eve Hinman of Hinman
Consulting Engineers (HCE) puts it. HCE, whose clients include the FBI,
The Pentagon, USAID, and the State Department, is one of the leading
companies in developing blast-resistant buildings. Sina Najafi and Eyal
Weizman met with Eve Hinman in New York to discuss the technology and
objectives of “hardening” buildings.
We would like to start by understanding what a blast does to a
building. Can you give us a kind of slow-motion description of the
event following the detonation of a bomb outside a building?
Well, an explosion is a chemical reaction that causes an extremely
rapid release of energy. This energy is released in several forms:
sound, heat—visible as the “fire ball”—and shock waves, consisting of
highly compressed particles of air propagating radially outward from
the explosive source at supersonic velocities. Of these, it is the
shock wave that is the primary cause of the structural damage. Released
energy pushes the air particles out. In addition to going into the air,
it also goes into the ground, and creates a crater. Some energy
propagates through the soil as well, creating “ground shock” that can
shake buildings, like a high-intensity, short-duration earthquake. The
shock wave exerts extremely high pressures on all surfaces that it
encounters in its path. The side of a building facing the explosion is
worst hit by the shock wave because the wall breaks the wave and forces
it to reverse its direction amplifying the peak pressure like ocean
waves against a particularly weak wave breaker. The shock wave travels
across and through the building, and in the process pressure is applied
on all the surfaces it encounters. After the initial shock wave, a wind
rushes in to fill the vacuum created, carrying high-velocity debris
which can cause impact damage.
How do different elements
of a building—concrete, steel, glass—respond to an explosion? What are
the factors that quantify the damage of an explosion?
glass breaks almost immediately as the shock wave hits it. The exterior
walls will bend inward and possibly also break. Once the blast wave has
entered the interior of the building, it will flow both upward and
downward and act on the floor slabs of the building. Since the floor
slabs have not been designed for upward load, they are particularly
vulnerable to collapsing in this direction. If the force of the
explosion is capable of failing a floor slab or column on the lower
floors, then a partial or complete collapse of the structure may be
initiated as the floors above come tumbling down. This “domino effect”
is known as “progressive collapse.” The vast majority of fatalities
occur in the collapsed portion of the building.
The skin of
the building is usually the most fragile part. These days, buildings
tend to be very, very thin, almost all glass and aluminum. So the skins
are very fragile and are crashed by the blast wave almost
instantaneously as it enters the building. Generally, it is quite hard
to knock out a column because columns do not have much surface area,
and the blast is looking for a surface, so it just kind of washes
around slender members like water. For a steel building, what you might
see is that the framing tends to stay in place—the beams and
columns—but all large surfaces, like floors and walls, are swept away.
And what does this pressure do to a human being?
If you’re hit by the pressure alone, it may cause lung collapse, which
can be lethal. Ear drum rupture is another possibility, but that’s
usually not lethal. The collapse of the building is the primary cause
of fatalities. People on the lower floors may be trapped in little void
spaces and be saved if the rescuers are able to get to them quickly.
People who are near the window are in most danger. They are the first
to be hit by flying bits of glass, causing lacerations; their lungs may
collapse, their eardrums may rupture, and the building may fall under
or on them.
So the corner office must be the most
dangerous place in the building. Should we now be rearranging buildings
so that storage spaces are near windows and offices closer to the
No, people are not willing to give up
windows. What we recommend is that at a minimum the VIPs’ offices not
be prominent. In other words, if you see the face of a building, there
should not be some huge multi-story area where it’s clear that
something special is going on. We don’t want to call attention
architecturally to the part of the building where there are going to be
people who are likely to be targets. Regarding glass—what we’re finding
is that glass wall systems have more ability to absorb blast energy
than previously thought. And we’re using laminated glass so that it’s
less hazardous. Still, glass affords a relatively low level of
When did individual buildings first become
targets in a significant way? In the 1970s, there were airplane
hijackings and bombs in public spaces, but I don’t remember buildings
There were three main stages in the
development of targeting and protection of buildings. The bombing of
the US Marine barracks building in Beirut in 1983 was the first and one
of the biggest truck bombings ever. Shortly thereafter, the US embassy
there was also bombed. After that, the US started to work on protecting
embassies from car bombs. The 1993 World Trade Center bombing and the
1995 attack that destroyed the Murrah Federal Building in Oklahoma City
brought the threat into the US itself and federal and landmark
buildings became fortified. Then there was the 1996 Khobar Towers
bombing in Saudi Arabia, and the 1998 embassy bombings in Nairobi and
Dar-es-Salaam, and finally 9/11, which inaugurated the corporate
world’s serious interest in security.
Up until Beirut, the US
State Department was mainly concerned about mob attacks—people climbing
over the walls and infiltrating the embassy. Beirut was, by the way,
one of the first suicide attacks, and it was a huge event—about 12,000
pounds of TNT explosive, which is still one of the largest vehicle
weapon that has ever been recorded. So, with the US embassy being
bombed, the State Department developed a set of new of criteria for
architectural security, and that is how I started to get involved in
this subject. I was working at the firm that developed those criteria.
This was the first document of its type and our work was immediately
applied to several embassy buildings.
One of the main
criteria we asked for was a 100-foot setback from the road, because
shock waves decay extremely rapidly with distance, and also that
buildings be built of reinforced concrete, which is how bunkers are
built. The windows were designed to keep all of the blast pressure out.
They were very thick in order to be blast-resistant.
these changes affected a very small inventory of buildings. The
Department of State owns about 400 embassy buildings. It was only the
Was that the first time you worked on blast-resistant engineering?
When I was hired, I was doing defense work. I was designing nuclear
missile silos and barracks in various NATO countries. But after Beirut,
my work changed from the field of “conventional” and nuclear warfare to
give answers for threats of unconventional, terrorist, and guerilla
How was Oklahoma City seen in relation to this “history” of the targeting and hardening of buildings?
After the Oklahoma City explosion, domestic federal buildings were
hardened. I was again part of the panel that developed a new set of
criteria and recommendations to tackle that. From that moment, the
tendency was to take the federal building—and this later influenced the
state department’s buildings abroad as well—outside of city centers and
into suburbs. There we were much more flexible in terms of our
considerations; we could afford to get rather insulated compounds with
large setbacks from the public areas, with wider views all around. The
density of the city exposes the building to a high degree of risk.
The domestic federal building inventory overseen by the DSA—the largest
landowner in the country—includes about 4,000 highly populated
buildings, which was still a relatively small market.
of inventors have begun testing new materials, new security and control
systems to resist explosion effects. These were implemented with lower
and lower budgets. Innovation in this field has accelerated after the
1996 bombing of the Khobar Towers because at that point the military
started to get involved, and its budgets and expertise were harnessed
to improve knowledge and procedure. So, then all of a sudden, the
barracks, buildings, and training facilities on military compounds both
in the US and abroad were being hardened.
So if Beirut
initiated the protection of embassies, Oklahoma brought about hardened
federal buildings, and the Khobar Towers set in motion the securing of
military installations, did 9/11 bring that into the corporate
architecture of the private sector?
Before 9/11, there
was a little bit of interest from the private sector until they found
out how much it cost, and then they would go away. But after 9/11, the
private sector is seriously taking up these concerns, particularly with
their underground parking. September 11 also opened up the market for
infrastructure protection: bridges, tunnels, train stations,
petro-chemical facilities, banking institutions. Within the private
sector, we’re seeing activity mostly with banking institutions,
insurance companies, and signature buildings in the city. In a small
city in the Midwest, they may have only one 50-story building, but it’s
the tallest building in their state, and they think it’s a target, and
they want us to help them.
Did this security mentality
filter into contemporary architectural and urban practices? Does the
government favor lower buildings now, for example? Are there
significant changes in the way cities are organized and do you advise
on changes at that level?
Yes, for example, government
officials always talk about cars—how to stop cars ramming into
buildings, how to stop cars from getting under buildings and blowing
up, and so on. But why, especially in a place like Washington, D.C., do
we really need cars at all? Why don’t we just get rid of the cars?
Nobody wants to talk about that, because we’re so reliant on vehicles,
particularly in this country.
Another thing is that now when
we ask for 50-foot setbacks for federal buildings, there’s more green
space, and this is good for the environment. In a sense we are starting
to see blast-resistant sustainable buildings.
Safety can be
enhanced through architectural countermeasures, and can be the least
expensive way to protect buildings. We provide functional and
structural design solutions for windows, entrances, and layout that
optimize protection without creating a building that looks like a
fortress. We usually consider moving vehicle and stationary vehicle
bombs, hand-carried weapons, and ballistic weapons. We work through
“what if” scenarios and make recommendations for improving safety
It’s interesting how aesthetics is so quick to accommodate the new agendas—security features camouflaged as public art.
I find that when I explain concepts of blast to architects, some of
them are interested and some of them aren’t. And those who are
interested will come up with all kinds of creative solutions to these
issues, particularly landscaping features. For the Seattle Federal
Courthouse, we designed essentially an obstacle course between the
street and the building at the front entrance. We placed a grove of
trees, and then a sunken sculpture garden and then a monumental
staircase and then this cascading fountain. It wasn’t completely
ram-proof technically—it doesn’t stop a vehicle from getting to the
building—but it makes it so difficult that it would deter most people
Do you know Richard Serra’s public sculptures? They’re probably very good for this purpose…
But they tip over easily. We did do something related to Serra with the
Liberty Bell. After 9/11, we were working with an architect who wanted
to protect the bell! And I was like, “An atom bomb could go off and
this bell should still be here.” I mean, it’s a big bell. But anyway,
they had curved, steel walls on opposing sides of the bell to protect
it, using your Serra concept. The walls were connected into the
But it wasn’t by Serra, was it?
No, but it was using the ideas he’s advanced.
seen on your webpage that you actually collaborated with Morphosis, Tom
Mayne’s architecture firm on a Federal Office Building in San
Francisco. When you work with contemporary, cutting-edge architects, do
you find that it’s easier to integrate security concepts into their
rather complex buildings?
Morphosis was a fabulous group
to work with. They are just very smart architects, and very responsive.
I remember going to a security meeting where security was telling them,
“You can’t do this, this, this, and this,” for various security reasons
that really didn’t relate to us. These security considerations had to
do with the fact that the building was located in a bad neighborhood,
where, as you know, there are homeless people who like nooks and
crannies where they can sleep or hang out. And that was considered a
threat. The architects just totally changed their design in response to
these “threats” very, very quickly and responsively. With some
architects, it’s just like in stone. If they’ve drawn it on a piece of
paper, that’s it. You can’t change it, and you end up coming up with
some clunky security solution because they can’t move a wall around.
know that in May 2003 there was a shootout with a gunman at a
Gehry-designed building on the campus of Case Western Reserve, and
afterwards the SWAT team had complained about the building, saying that
all their training for sweeping buildings and for returning fire
assumes a specific kind of architecture. “There are no right angles in
the building,” was the complaint of Chief Lohn of the Cleveland police.
Do you have any thoughts about that?
There’s a whole
discipline called CPTED—Crime Prevention Through Environmental
Design—which deals with how architecture can thwart criminal activity.
Things like little nooks and crannies of the building where people can
pull somebody into and nobody will see them are discouraged.
From a purely explosive perspective, we would like more of a convex
shape rather than a concave shape—something like a hemisphere would be
good—to reflect the pressure away.
So Gehry is good?
Well, he’s got both the concave and the convex. What happens in the
concave areas is that the blast pressure reflects a lot and it
amplifies. It’s also important to have a very stable construction, such
as a pyramid shape.
The arms race between security and
terrorists has shown sometimes that the more security, the more violent
the attacks tend to be. This is how plane hijacking got radicalized
since the 1970s. Do you not think that perhaps security and prevention
could be counterproductive in a certain way?
Yes, this is
why we want the protection to be as unobtrusive as possible, so as not
to draw attention to the building, or turn it into a fortress, which
may cause threat escalation. For federal buildings, they still want the
buildings to keep a feeling of openness, which they think is consistent
with what democracy is about.
When you say “unobtrusive,”
do you mean to protect the building without signaling that it has to be
protected in this particular way? Because, presumably, part of the way
security works is that you also announce it loud and clear: “This
building is secure.” Or no?
No, no. Building owners, I’d
say, uniformly do not want attention brought to their building, and
they do not want anybody knowing that they’re upgrading their buildings
security-wise. They don’t want to make any announcement to draw
attention to themselves—that already makes them more of a target. I’d
say within certain sectors, some clients go way out of their way to
make protection measures look like routine maintenance or to disguise
it as something else.
From the government’s perspective, by
fortifying one building, you actually direct attacks to other, less
fortified ones. In that respect, the government applies what it calls
the “good neighbor policy,” whereby if they have a little fort in the
neighborhood, they feel they are making the rest of the neighbors more
When we were doing the embassy criteria, we
decided that we must provide the same level of protection for all our
embassies, because by not providing protection to one embassy, you’re
creating a vulnerability that will draw attacks. On the same level, if
you harden a building in Manhattan, you must be careful that you are
not driving terrorists into smaller towns in search of targets.
you mentioned, there were initially 400 embassies protected, then came
the 4,000 federal buildings, then the much larger inventory of armed
forces installations, and now the private sector. Now that all these
are secured, what is left soft and unsecured is much more threatened
and must also invest in security. If you secure one thing, you finally
have to secure everything. The logic of endless fortification means
that Vermont has to be as fortified as Manhattan and Iraq. And even if
you secure all buildings, the people in the subway might be targeted
instead. Where does all this end?
There has to be a
distinction between what we are doing domestically and what we are
doing in war zones. Domestically, you want to have at least the
appearance of a uniform level of protection to keep out the “lazy
terrorist,” to deter the most obvious simple-minded and yet devastating
execution of events, which means parking a Ryder truck 10 feet away
from the building and detonating thousands of pounds of fertilizer
bomb. Certainly, there have to be measures to keep weapons away from
the building because it’s just too easy to execute. Eliminating that
scenario is the goal, rather than trying to stop airplanes from flying
into a building.
But “buildings as targets” have a longer
history than that of contemporary terrorism. You’ve said that the
terrorists don’t abide by the rules of warfare. We completely agree.
But I think that warfare itself has not abided by the rules of warfare
for a long time. Bombing civilians has been going on on the good guy’s
side as well for a long, long time…
The difference is
that the terrorist event is a relatively low- budget single event; The
9/11 events, I forget how much they said it cost, maybe a couple of
hundred thousand dollars...
Does this industry have an end point?
You must understand that all this depends as well on a growing market
that pushes security as a product. Because basically the economy isn’t
doing that well, and everybody thinks that there’s money here,
everybody is all of the sudden a security expert—and convinces building
owners that they are under threat.
Eve Hinman is founder and principal engineer of Hinman Consulting Engineers. Her 20 years of experience includes designing nuclear missile silos, NATO military facilities, industrial buildings subject to accidental explosions, and civilian buildings vulnerable to terrorist attack. She is the co-author of Lessons from the Oklahoma City Bombing: Defensive Design Techniques.
Sina Najafi is the editor-in-chief of Cabinet.
Eyal Weizman is an Israeli architect based in London. He is professor of architecture at the Academy of Arts in Vienna. Weizman is the co-author of A Civilian Occupation (Verso).
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