New Solutions for Old Bridges
Mathias-Riegel, Barbara, ASEE Prism
It's a good thing the civil engineering lab at Bucknell University is a substantial size, because in it sit two 36-foot round logs cut from 60-foot used telephone poles, complete with a small dose of creosote. It's a timber bridge designed and built by two civil engineering students, Megan Strand and Linda Steele. Commissioned by the Borough of Lewisburg, Pa., the bridge will cross over a small stream in the township.
The job is done, but the logs remain until the abutment of the existing bridge is removed. Jai B. Kim, chairman and professor of Bucknell's department of civil and environmental engineering, doesn't seem to mind the delay. He likes looking at them every day. "They are very romantic," he says.
"Romantic" may seem a funny word, but Kim is passionate about bridges and especially about the preservation of historic bridges. It all began nearly forty years ago when he was an undergraduate at Oregon State and designed a logging bridge for a lumber company. From there he went to Bucknell where he taught and developed the Bucknell System, a method of strengthening metal-truss bridges by building new arches that help carry the stress load on the pin connections. Now a consultant on metal-truss bridges, Kim brings his passion into the classroom where his students routinely watch videos on historic bridges.
"Think about the Romans," Kim tells his students. "They have 2,000-year-old-structures; we don't even have 100-year-old bridges. When I read about dynamiting the bridges, I get sick."
He also gets busy. To date, Kim has supervised nine bridge projects with his students. His most recent is the 132-year-old Henszey's Wrought-Iron Arch Bridge that spans Ontelaunee Creek, situated on rich farmland near Harrisburg, Pa., about 90 minutes from the Bucknell campus. Ninety-two feet long and 18 feet wide, Henszey's bridge is a handsome sight, with its wooden floor and bow-like arches. In 1985 it was deemed unsafe and shut down with cement barricades at both ends.
"It sat on the site and was just rusting out until the president of Central Pennsylvania College, a 600-student proprietary institution near Harrisburg, called the Pennsylvania Department of Transportation and asked if they had any old spans," says Kim. …