Old Bridges Give UMass Amherst Engineering Students Hands-On Education in Structural Mechanics and History

October 31, 2008

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AMHERST, Mass. – Alaska may have its bridge to nowhere, but two University of Massachusetts Amherst professors of civil engineering want to put this campus on the map as the only school where structural engineering students can gain hands-on professional experience by rebuilding historic bridges, with the added benefit of preserving significant pieces of New England’s technological past.

Alan Lutenegger and Sanjay Arwade won a $150,000 National Science Foundation grant for the project, which will allow student engineers to repair and relocate at least two old iron and steel truss bridges on footpaths around the campus over the next couple of years, with six or seven more in line to be added later. About 85 graduate and undergraduate engineering students per year study course materials related to the bridge project, Arwade says. Of these, four or five per year who choose advanced research will gain significant hands-on skills in material testing, structural analysis, site preparation and construction by fabricating new parts and putting the bridges together again.

“It’s not unusual for towns and villages to preserve these smaller old bridges for pedestrian uses,” Arwade says, “but it is very unusual to preserve them as we are for engineering education.” The UMass Amherst project addresses a long-standing problem in structural engineering education, he and Lutenegger feel. That is, in Arwade’s words, “it’s hard to do laboratory experiments that seem real because civil structures are so big. You can’t bring a bridge into a lab. We don’t want our students to miss out on doing experiments with something that’s real, which is where the bridges come in.”

One bridge that students have already measured, tested, repaired and relocated is a 40-foot 1906 Warren Pony Truss Bridge from a southern Vermont town, which is now on a footpath between the university football stadium and track. For their engineering courses, students are still gathering test data this month, while the weather holds, to answer questions such as how much the deck would deflect under a heavy load – a 19,000-pound bucket-loader, for example. The recent NSF grant means two more bridges can be relocated soon and several more are in storage on campus in various states of disrepair, the two professors note.

Truss bridges, many hundreds of which were built up to the early 1900s in New England and elsewhere, use triangle-shaped supports in a design simple enough that small wooden bridges were often made with hand tools. The continued safe use of hundreds of old iron and steel truss bridges still in service around the country, Arwade and Lutenegger point out, depends on civil engineers’ knowing how they respond to stress and when repairs are needed.

For the UMass Amherst project, students first measure all the parts of each bridge and use computer-assisted design software to create accurate plans and drawings. They identify parts that need refurbishing, then cut steel to length in the machine shop, prepare notches and bolt holes, and fabricate a new part. The student engineers add new decking or side rails as needed. Finally, they create site plans for a foundation at the new location.

Lutenegger says he began in 2001 collecting retired bridges taken out of service because they’re too narrow, can’t carry heavy modern vehicles or because of corrosion and safety concerns. “These bridges are an important part of our technological heritage, particularly here in New England, and they’re growing increasingly rare. It would be a shame to see these bridges completely disappear from the landscape,” he says.

Thanks to Lutenegger’s collecting, future structural engineering students here will be rebuilding a fairly rare Ball Pipe King Post truss bridge manufactured in the late 1800s in East Windsor, Mass., donated to the university by the Windsor Historical Commission. It served for about 100 years in Dalton before being retired in 1990. Only three are known to survive today.

Similarly, at one time about 800 graceful lenticular truss bridges were believed to be in service across the country but now only 40 survive, nine of them in Massachusetts. Lutenegger hopes to obtain the 76-foot Golden Hill Road bridge over the Housatonic River in Lee, Mass. for the UMass collection because it is scheduled for replacement. Lutenegger and Arwade also have their eyes on another rare New England bridge, only three of which survive.

The bridges will eventually be part of a technology history tour with interpretive signs and downloadable audio guide at UMass Amherst as a scientific and cultural resource to be shared with engineering students from other institutions, history buffs, the public and school groups.

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