UF researchers laser mapping WTC, Pentagon sites

October 3, 2001

GAINESVILLE, Fla. — People who live and work in buildings surrounding the former site of the World Trade Center may feel safer once a unique project to precisely map the damage is completed, says a University of Florida researcher.

“The recent attack on the World Trade Center and Pentagon has not only created a human tragedy, but infrastructural devastation as well,” said Dave Bloomquist, a UF professor in civil and coastal engineering who is a member of the project team. “Besides the hundreds of thousands of tons of debris, several surrounding buildings near ground zero may not be structurally salvable, and there is concern that several are slowly deteriorating.”

When a building is damaged, standard surveying techniques are traditionally used to assess its condition, but the process is time-consuming and only a few select points are scrutinized, he said.

Faculty and students in UF’s civil and coastal engineering department are part of a multi-agency collaborative effort to use an entirely new technique to get detailed pictures of the World Trade Center and the Pentagon that relies on both airborne laser swath mapping, or ALSM, and ground-based scanning laser technology, Bloomquist said. From it, hundreds of millions of laser range measurements can be rapidly collected and analyzed of the precise three-dimensional positions of points covering the surface of the ground, buildings and rubble in and around ground zero, he said.

The UF-led team collected the first ground observations Sept. 23, twelve days after the attack, from a 10-square-mile area around the World Trade Center, Bloomquist said. When the FAA allows aircraft to fly over the affected site, the team will collect aerial data using both laser and digital photography.

“When the airborne and ground-based observations are combined, they will provide the information to make three-dimensional models of the disaster sites far more detailed and accurate than has ever before been available to recovery workers and planners,” he said.

The National Science Foundation has awarded a $45,000 grant for the project.

UF has had a research program for more than four years in the application of ALSM to a wide variety of problems. Working collaboratively with Florida International University, UF was the first academic institution in the United States to buy and operate an ALSM unit. Since then, UF researchers have completed more than 25 research projects funded by federal, state and local agencies. Some of these include landslide detection and monitoring, sinkhole assessment and coastal effects from hurricane damage.

While structural engineers have surveyed the adjacent buildings for structural integrity, the potential for additional damage exists, he said.

Researchers hope to detect any damage to the foundation by learning whether building walls are still vertical planes as well as if there has been any bulging as a result of the building shifting, Bloomquist said.

“This large a shock to the foundation could damage some of the pilings that buildings are set on,” he said. “When the World Trade Center towers collapsed, some seismographs picked it up as if it were an earthquake.”