By Michael Jay Tucker
The building is enormous. It is concrete. It is full of steel. It reaches many stories into the turquoise sky. All around it is a teeming city.
There is traffic in the streets. Huge and delicate office suites of glass and steel are right next door. And nearly a million people live nearby.
Yet the building is decaying. It is abandoned and crumbling. Police have had to remove squatters several times. It is a danger to the city, and must be removed. But how to do so without creating even more of a threat?
There is a sound of sirens, then a deep, almost subliminal explosion. And slowly, almost gracefully, the building seems to melt into itself. The glass suites are unharmed. The traffic hurries on. The million people barely notice.
|Down with a bang. Building demolition is the art of safely bringing down structures such as the Biltmore Hotel in Oklahoma City, which was successfully imploded with the aid of CAD tools by Controlled Demolitions Inc.|
Building demolition is among the most demanding, and the most flamboyant, of all the "construction" industries. Its practitioners must be able to take vast structures and turn them to rubble without in the process disturbing their surroundings.
How do they do that? The answer, of course, is with great difficulty. And demolition experts, the people who do it, are a special breed. Luckily, computer-aided design-or in this case, computer-aided destruction-can make their lives just a tad easier.
"People think that we're just taking a wrecking ball and smashing things," says Damon Kozul, vice president of RecMediation, a demolition and reclamation firm based in Jamesburg, New Jersey. "But it isn't that at all. It's a complex business."
And indeed it is. Michael R. Taylor, executive director of the National Association of Demolition Contractors (NADC), notes that the North American demolition industry is composed of "1000 to 1200 companies, all privately held." This isn't, in other words, a market of large, publicly traded corporations. It's too much a market niche for that. But this isn't to say it's small. "It [the demolition industry] has gross sales of between $3.5 and $4 billion annually," notes Taylor.
The players in the field can be broken down according to size and (sometimes) specialization. Says Taylor, "The market is made up of three basic types of companies. There are about 50 national firms that work all over the United States and Canada. Then, there are regional players, say, companies that work only in New England or the Southwest. And, finally, there are subcontractors."
Among the subcontractors will be some of the most colorful of the specialists-for instance, the "imploders" (as they're called by people in other branches of demolition), who will destroy structures with explosives. Indeed, perhaps the most famous firm in demolition is an imploder, Controlled Demolitions Inc. (CDI), whose spectacular projects have become hugely popular public entertainment-complete with fireworks and music. "I'm a licensed pyrotechnician," notes CDI's Stacey S. Loizeaux, who describes herself and her sister, Adrienne, as "third-generation" members of the business. "We do get calls now and then for fireworks along with our implosions."
|In demolition, CAD is as much a road map as it is a modeling tool. With it, as in these steel mill drawings from demolition company Brandenburg, contractors can keep track of utilities such as high voltage lines that could endanger the project-or peoples&|
Thus, for example, on December 31, 1996, CDI turned the Hacienda Hotel of Las Vegas into the biggest New Year's Eve fireworks display in history. And, in 1991, its demolition of the old Orlando City Hall was a featured special effect for the movie Lethal Weapon 3.
But does CAD have a place in any of this? While it is not being used to simulate the explosion, per se, it is playing a valuable role in the planning process. In the demolition process itself, most contractors don't use computer models. That's partly, says Taylor, because demolition people tend to be hands-on types. "They like to see the work they're doing," he says. "They won't go over a CAD drawing. They'll go into the field and see the site itself."
Then, too, the actual demolition can be so complex that it is simply beyond what a CAD package, or any current system, can model. That is particularly true for the people using explosives. "There are just too many variables," explains Loizeaux. "In fact, a company approached us several years ago with this concept to determine if pre-implosion modeling would serve us in any way. The answer? Nope. Here's why: The diversity of structures we deal with, and the number of variables that are present on any given project-and others that would have to somehow be factored into the computer program-are absolutely astounding."
Specifically, she notes, "Just to give you a few examples, if a structure were made of reinforced concrete, you'd need to be able to plug in such things as: Where'd they get the sand they used in the concrete? What's the average temperature in the area? What's the average rainfall? What type of fill is the structure built on? Has the structure moved over the years? Who built the structure? Did they take shortcuts? What type of reinforcing bar has been used? Is it recycled?" And that, she notes, is just the beginning.
But if CAD isn't used in the actual bring-down of the structures themselves, it does have a place every step of the way up to that point. "You have to have everything designed beforehand," says Ron Elliot, a vice president at Pacific Blasting. "You can't just rush in without having any idea of what you're doing."
In fact, this is where CAD shows up first. Many is the demolition firm that uses a CAD program (usually AutoCAD) to lay out in exacting detail what it is workers are about to jump into. For instance, at Pacific Blasting, the technology is used for drilling plans. "Let's say that on each floor, you're going to have charges placed in each of the support columns on that floor," says Elliot. "You've got to drill two holes, for two charges, in each column. And you've got 25 columns per floor." There will be 25 more columns on the next floor, and on the floor above that, and so on, for many hundreds of columns.
|Before a building is demolished, its structure must be carefully examined-often using CAD models-to determine the ideal locations for explosives.|
Then, the demolition person has to work out a means of labeling each and every hole, each and every column, and each and every piece of explosive, "so you can know at a glance where any one charge goes," Elliot says. In a large building, that can get messy. "You can spend weeks preparing for a blast," he notes. Which means that you may be best off using a CAD program, if only to give you a road map of what's where, and if it might explode. To that end, Pacific Blasting uses DesignCAD, from Oklahoma-based Upperspace Corp., running on Windows-based PCs.
That's only one benefit of using CAD in demolition. Another is worker safety. "The bread and butter of our company is the demolition of steel mills," says Mark Cerven, project manager of Brandenburg Industrial Service, a demolition company based in Chicago. "That doesn't mean just closed steel mills. It also means working mills. A lot of times, you have a mill owner who wants to close down one area, but keep another area running."
Consider how difficult a proposition that is. A steel mill has, by definition, large buckets of things like molten metal hanging about. There are live, high voltage lines everywhere. There will be pipes of pure oxygen running to blast furnaces. "When you go into something like that," says Cerven, "you have to have a handle on the utilities." If you meet up with a live wire or some other hazard, it could kill you. Or you could accidentally shut off power to the whole factory, which means "a loss of millions of dollars a day. And the mill will charge you, the contractor, for that loss."
All of this is powerful motivation to make certain you don't do something like that. But, alas, you may not have the data you need. "About 15 years ago, our company president was doing that sort of work on a steel mill," says Cerven. "He asked the mill's high voltage guy for a map of the lines in the area. The guy brought him a hand-drawn, 8- by 11-inch sketch that basically showed nothing."
It was at that moment that the company decided to bring in Cerven to set up a CAD operation. Cerven says his company uses generic PCs running AutoCAD 2000 on Windows. He notes that his firm had tried Unix systems on HP Pentium IIIs, but found it was simply easier and cheaper to go with Windows. Now, for each project the company begins, Cerven can gather everything known about the site and have it available in an easy-to-view CAD drawing. "And we can put it on the Web, where everyone has access to it."
Which brings us to the third role CAD has in demolition-clarity in communication. Cerven uses CAD, and the Web, to make certain that everyone involved in a project has access to all the information they might need. That includes the client. "Before, we might give them [the client] a set of blueprints marked up with highlighters to show what would stay and what would go," notes Cerven. "Now, we can give them a completed CAD graphic showing exactly what is going to happen." It's both more informative and more professional.
It may be that this third role-communication-is the most important one that CAD has in the demolition industry. It can help everyone involved in a take-down project understand precisely what they're getting into, and what's needed of them. Thus, notes CDI's Loizeaux, "The main use of CAD in our work is to prepare drawings of the structures' floor plans to demarcate walls to be removed, drilling operations to be performed, explosives placement, delay patterns, protective covering materials to be placed, etc." In fact, she says, "We've been using AutoCAD for several years now to prepare drawings demonstrating CDI's preparation operations to be performed on the structures we demolish. The CAD system has proven invaluable in that application." She says that AutoDesk's AutoCAD on PCs is her company's standard.
So, in short, despite the fact that CAD doesn't seem to have a role-at the moment-in modeling the actual demolition, it is very much a part of the demolition process. And, it's a role that could grow over time. "Demolition people are pretty computer savvy," notes NADC's Taylor. "They're always interested in things that make them more productive. Computer-aided destruction may be the wave of the future." Michael Jay Tucker is a freelance writer based in Winchester, Massachusetts. He can be reached at firstname.lastname@example.org.