PROSPECT, Maine — The aging Waldo-Hancock Bridge may have a role to play in homeland security before and after it is torn down.
The U.S. Department of Homeland Security is working with the state Department of Transportation and the Federal Highway Administration to conduct tests on the 77-year-old span as part of an ongoing study of suspension bridges that could help authorities better protect the nation’s bridges from terrorist attack. The study will involve limited on-site testing as well as more extensive off-site tests — including explosives testing — on sections of the bridge as it is being dismantled.
“Bridges are part of our country’s critical infrastructure,” Homeland Security spokeswoman Amy Kudwa said Friday. “We are constantly looking for ways to protect and harden that critical infrastructure.”
DHS committed $400,000 to the testing program for the 2008 fiscal year. Although the program is considered a multiyear program, Kudwa said no additional funding has yet been committed.
According to Kudwa, the on-site tests will look at vibrations and how they affect the bridge.
“As the bridge is dismantled, we will be taking some sections of the bridge for testing purposes,” Kudwa said.
Crews from the DOT and U.S. Army Corps of Engineers were on the bridge for several days earlier this month conducting tests. Some of the tests created explosionlike booms that echoed up and down the Penobscot River near the bridge. Those tests on the suspension cables of the bridge were designed to study their response to dynamic loadings, according to Doug Hecox, a spokesman for the Federal Highway Administration. The loud booms that people heard frequently during the testing “came from the ‘cold-gas thruster’ tests conducted mimicking the larger-magnitude excitations of interest to the researchers,” Hecox said.
Although some of the tests sounded like explosions, they were “nondestructive” tests and did not damage the old bridge or the new Penobscot Narrows Bridge nearby.
Because of the proximity of the Penobscot Narrows Bridge, Kudwa said, there will be little actual on-site testing.
Once the state begins to dismantle the bridge, however, DHS researchers will take selected sections of the structure for remote testing, including full-scale explosive demolition at a secure facility, according to Kudwa.
The Homeland Security Department uses a network of test facilities around the country, including its own laboratory in Atlantic City, N.J. No specific arrangements have been made yet for the off-site testing, Kudwa said.
The study is designed to give DHS researchers an idea how older bridges react to specific stresses.
According to Kudwa, DHS’ Science and Technology Directorate, the research and development arm of the department, has been conducting testing on computer models and on models built of modern materials using modern construction methods.
Using the Waldo-Hancock Bridge gives researchers the opportunity to study bridge elements constructed with early 20th century materials and methods that have been subjected to decades of environmental effects and traffic.
Those tests should provide the department with better information for research and development of methods to protect existing structures around the country, according to Kudwa.
The Waldo-Hancock Bridge was undergoing a multimillion-dollar renovation in 2003 when the DOT uncovered deterioration in the main cables that eventually forced the department to replace it. It was closed to traffic on Dec. 30, 2006, when the new Penobscot Narrows Bridge was opened, and is slated to be torn down.
The DOT has not set a specific date for dismantling the bridge, but funding for that project was included in a four-year bond package approved by the Legislature earlier this year. Dismantling of the bridge could begin within the next four years.