As the country marks the 10th anniversary of the Sept. 11 terrorist attacks, a Vicksburg engineer whose work was key to saving hundreds of lives at the Pentagon that day views it as the highlight of his career.

Robert Hall, 62, is a 38-year veteran of the U.S. Army Corps of Engineers, most of that at the Engineer Research and Development Center on Halls Ferry Road.

He led the team that developed building supports and materials credited with keeping a section of the Pentagon from collapsing in the minutes following the impact of American Airlines flight 77 at 8:37 a.m. central time.

“Anytime you do anything that is used is good,” Hall said in a recent interview. “The fact that what you’ve done has saved lives is — it’s the highlight of your career. You never dream …. you always hope that your product and your research works, but for it to be tested and for it to be proved to work successfully, and then for it to save lives is… it’s indescribable.”

The Boeing 757 that terrorists crashed into the Pentagon at about 345 mph had taken off from Washington’s Dulles International Airport carrying 10,000 gallons of fuel. The deaths included 125 Pentagon employees, 55 of them members of the military, as well as the 59 passengers and crew onboard the aircraft.

The first two floors of the impact section were obliterated by the crash and firebomb from the jet fuel, but the third, fourth and fifth floors did not collapse for more than half an hour, allowing many to get out of the building where sections continued to burn for hours. In addition, nearby sections that had recently been renovated with reinforcements developed by Hall and other ERDC researchers were largely undamaged.

“We had offices very close to the impact that were fine, and other offices 100 or 200 feet away that were completely blown out,” said Wayne Stroupe, public information officer at ERDC.

“Those retrofits saved lives,” Hall said simply.

Hall, a native of Crestview, Fla., came to Vicksburg in 1971 as a Mississippi State University graduate student working with the Corps of Engineers Vicksburg District. Within a year he moved over to what was then called Waterways Experiment Station.

“I came here to work on my masters and then go to a better life,” he said with a chuckle. “Then they sent me off to school to get my Ph.D. …” — and Hall ended up staying, rising to chief of the Geosciences and Structures Division of the ERDC’s Geotechnical and Structures Laboratory before retiring in 2009.

Scientists at ERDC began looking at improving the ability of structures to withstand explosives in the 1980s, Hall said, first against smaller “briefcase” explosives and then progressing as terrorists built larger and more destructive bombs.

“ERDC has been involved in anti-terrorism ever since the bombing of the Beirut Marine barracks (in 1983), the Khobar Towers (1996), Oklahoma City (1995), the first bombing of the New York City Twin Towers (1993), all of those,” Hall said. “After the bombings of all the embassies overseas, we’ve worked with the Department of State and several different government agencies in protection of their critical infrastructure.”

Tests were carried out on small- and full-scale models within ERDC’s experimental buildings and areas as well as off-site test areas at the Big Black River and Louisiana’s Fort Polk, he said. In cases where the full-scale is the size of the Pentagon, they’d work on components or quarter-scale models of components, such as a parking garage.

“Yes,” he laughed, “they gave us permission to blow things up, but also (to) simulate with computer applications. Physical experiments are very expensive, so you want to be able to do that numerically on the computer as much as possible.”

They worked to predict how a wall would react to an explosion — how it would break, how much debris would be cast around inside the room, what would happen to bricks used in its construction or to embedded windows.

“You have to tie that window frame to the floor above and below, otherwise you just blow the wall out,” he said. “When that blast comes in, one of the greatest hazards is the breaking of the glass, and also that unreinforced masonry then becomes a projectile.”

In addition to structural supports, Hall and his team experimented with lining the inside of walls with a membrane, a so-called geo-fabric.

“We started anchoring it at the floor and the ceiling, and it turned out that that material ended up preventing those unreinforced masonry pieces from becoming projectiles, and protecting the people inside,” he said. That technology was further developed by the Protective Design Center, a sort-of sister Corps agency of ERDC’s in Omaha, Neb., he said.

“They took that technology and matured it, and that got transferred to the Pentagon,” he said.

The “window-wall retrofit” had been completed in most of the areas of one wedge of the Pentagon on the day of the attack.

“It is a terrible way to get the increased visibility and attention ERDC received after 9/11, but I’m glad we had the kinds of people who were able to tackle those problems and to produce solutions that really work,” said Dr. Jeffery Holland, ERDC’s director.

After Sept. 11, the Corps worked with military officials to get the Pentagon rebuilt within a year. Since, ERDC, which today spends about $1.2 billion annually at its seven research labs, has stepped up anti-terror research. Some of that overlaps with work done to protect overseas military.

“We always knew that what ERDC was doing was important, but the impact of what we were doing to support the nation’s military just really accelerated tremendously after Sept. 11,” Holland said. “I would say half of today’s total ERDC budget is antiterrorism-related, and our budget has tripled since Sept. 11. So our largest increases are all in antiterrorism-related work efforts that support our military and our nation.”

Some of the specific technologies are protected by security concerns, but areas include all of the locks and dams the Corps of Engineers manages, most of the major tunnels and bridges in the U.S., border security, and even terrain and data analysis, Holland said.

In retirement, Hall has continued his association with ERDC as a contractor, and is a consultant to other agencies and businesses. Hall and his wife, Jeanine, the president of Engineering Innovations, have two daughters — one who lives in Vicksburg and like her father is an engineer at ERDC, and one a doctor of internal medicine in Mobile — and five grandchildren.

He has been a member of Bowmar Baptist Church since his coming to the city, serving as church deacon and elder, a member of the strategic planning committee and a teacher of youth and adult Sunday school classes for many years.

“I enjoy that,” he said. “I enjoy the people.”

He also likes to hunt and fish and serves on the board of Habitat for Humanity.

As Hall looks back on the 10-year response of Americans to the Sept. 11 attacks, he said he is proud of the role his work played but thinks people need to enjoy the freedoms they have.

“Even though we work so much in this protection area, I think people have to realize that if we try to protect everything, we protect nothing,” he said. “We are in a free society and freedom has risk. I think the society has to learn not to overreact to these terrorist activities, but appreciate the freedom that we have and realize that that freedom has a cost. We need to focus more on our freedom than on trying to hide behind reinforced structures.”