By Joe Tash
Engineers loaded 32 tons of steel plating onto an aluminum bridge erected in the parking lot of an industrial complex, just a bungee jump away from the throngs eating deep-fried Twinkies and riding roller coasters at the San Diego County Fair.
The purpose of the exercise was to test whether the bridge, built and designed by ATA Engineering, Inc., of Del Mar, could actually handle the load as predicted by computer models during the bridge’s design. To the engineers and students who built the bridge, the test was the culmination of three years’ work, and maybe even as exciting as a day at the fair.
“It was fun for them (the students) and fun for us,” said Gareth Thomas, vice president and technical director of ATA Engineering, of the bridge project.
The company took on the task of designing a portable bridge system for the U.S. Army under the Small Business Innovation Research program, run by the U.S. Small Business Administration in conjunction with 11 different federal agencies, including the Department of Defense.
The charge was to create a “bridge in a box,” that could be loaded into a shipping container, flown to a distant location, and erected in 30 minutes by just two people using specialized equipment, said Thomas, who spearheaded the project’s design.
The result of the research — and several months of cutting and drilling aluminum beams by a team of UCSD engineering students paid $14 an hour — was a prototype bridge weighing 7,000 pounds, comprised of six interconnecting modules.
The prototype bridge is 42 feet long and designed to carry a load of 60,000 pounds, said Adam Price, an aerospace engineer with ATA Engineering who also worked on the project. The full-scale model of the bridge would span 66 feet and carry up to 100,000 pounds.
“What we’ve developed is really a bridge system,” said Thomas. “This design can work for 50-ton tanks.”
The bridge is designed to fold up like an accordion and fit into a standard shipping container, which in turn can fit in the hold of a C-130 cargo plane used by the military.
“If it’s in a (standard) container, it can ship by road, rail or air anywhere in the world,” said Thomas.
The company rented a warehouse on Jimmy Durante Boulevard, next to the fairgrounds, where the bridge was built. It will now be packed up and sent to Michigan, where officials with the Army’s Tank Automotive Research, Development and Engineering Center, or TARDEC, will evaluate it further and decide whether to order full-scale models.
According to Price, the bridge is the largest project the Del Mar company — which has 90 employees, most of them engineers — has actually built from scratch; most of its work is for the aerospace industry, for which it conducts structural analysis of satellites, rockets and airplanes.
The company also conducts structural analysis of roller coasters for Southern California theme parks, he said.
The bridge resembles an oversized erector set, and because of its modular design, it can be adapted to various lengths, widths and load limits.