The Jonathan Hulton Bridge in Oakmont may be painted lilac, but its planned demolition by the Pennsylvania Department of Transportation shows that when it comes to historic bridges, they often come in shades of gray.

Built in 1908 and named for a local landowner, Jonathan Hulton, the Hulton Bridge is the only span of its type -- known as a metal through-truss -- that is active over the Allegheny River. It was the first major bridge designed by Allegheny County.

But its early 20th-century design, innovative at the time it was built, was never intended to handle the 24,000 cars that pass over it daily from Freeport Road to Allegheny River Boulevard 101 years later.

Though still judged structurally sound, its narrow width causes traffic backups. Earlier this year, PennDOT announced that it planned to build a $75 million, four-lane, concrete beam bridge slightly upstream of the Hulton, then demolish the old bridge by 2012.

Enter the engineers, historians and bridge fans who argue that the legacy of historic spans in Pennsylvania is in danger of disappearing.

In a Post-Gazette article in July, Eric De- Lony, chief emeritus of the Historic American Engineering Record, said the state's remaining truss bridges would be destroyed by 2016 if not protected by preservationists.

HAER is a program of the National Park Service that designates heritage sites having to do with engineering, industry and technology.

Mr. DeLony cited three local bridges as significant and endangered: the 1888 Dorrington Road bridge in Collier, now demolished; the 1906 Charleroi Monessen bridge in Charleroi, condemned in February; and the Hulton Bridge.

Another local bridge preservationist, Todd Wilson, an engineer, said Mr. DeLony's article prompted him to suggest the possible salvation of the Hulton Bridge as a student project to Carnegie Mellon University professor Susan Finger.

Ms. Finger teaches a junior-level course for civil and environmental engineering majors, and Mr. Wilson serves as CMU's junior practitioner adviser for the American Society for Civil Engineers. He assisted with the students' Hulton Bridge project, which the students presented to the Oakmont community Dec. 8 during a meeting at Oakmont Country Club.

At the meeting, some of the eight students who had worked on the project presented their idea: preserving the Hulton Bridge as a pedestrian and bicycle route that might serve the Allegheny River Trail, which is scheduled to be extended from Downtown Pittsburgh to Armstrong County on the Allegheny's north shore.

Gabriella Briffa, 20, from Long Island, N.Y., said the idea was received with some interest by the meeting's attendees, who included residents, borough officials, the Pittsburgh History and Landmarks Foundation, the Oakmont Historical Society and PennDOT.

She said her group envisioned a pedestrian bridge beautified with flower boxes.

"Bridges that have been become pedestrian and bicycle bridges are just a different experience for the people that use them," she said. "The idea is that historic bridges become tourist attractions, and communities are proud of them."

Cassandra Abernathy, Dyanna Becker, Janice Chen, Andrew Ko, Zachary McCabe, Jon Nardolilli and Christine Peters are the other students in the group.

The students' proposal also includes placing pedestrian safety rails, spot painting and decorative lighting.

They estimate that the conversion of the bridge could be as low as $300,000, and say that some of the $6 million to $10 million that would be required to demolish the bridge could be used to refurbish it instead.

The students studied successful vehicle-to-pedestrian bridge-conversion projects, such as the Hot Metal Bridge on Pittsburgh's South Side, and claim that tourism sparked by the bridge could bring in an estimated additional $250,000 to $500,000.

They also sent surveys to Oakmont residents, and say that local support for keeping the bridge is strong.

"Eighty percent of people want to make the bridge part of the trail network, and almost half said they would volunteer to support the bridge-conversion project," Ms. Briffa said.

The biggest obstacle, she added, would be to find an individual or organization willing to legally take responsibility for the bridge -- as well as any costs associated with its refurbishment and ongoing repairs.

PennDOT's assistant district executive for design, Cheryl Moon-Sirianni, said she was "extremely impressed" by the students' presentation -- but they may not have been aware of all the obstacles to their plan.

"There are a lot of stakeholders involved that you might not think about. They had a lot of great info and did great research, but there's a lot that comes into play when we're talking about a bridge this large."

Although the Hulton Bridge would no longer accommodate vehicles under the students' plan, the engineering standards for pedestrian and bicycle bridges are still very high -- and would have to be maintained for the life of the bridge.

"Because bridges like this are often used for festivals and weddings, it would have to stand up to a load-bearing capacity equal to someone standing on every square foot," Ms. Moon-Sirianni said.

Bicycle bridges require more lighting for safety, a big expense, and because snow is very heavy, maintenance funds would have to be allotted for snow removal. Emergency and snow-removal vehicles would have to be able to reach the middle of the bridge.

The bridge's truss design is historic, agreed Ms. Moon-Sirianni. But the span also lacks the fail-safes that are built into today's bridges, and even though it is considered safe today, it will quickly fall out of compliance without costly annual repairs.

Keeping the bridge also will require that the entrance to the new span be moved closer to structures on the shore, including condominiums.

"Nobody wants to tear down a historic bridge," she added. "But this bridge has exhausted its design life."

Borough Manager Bruce Jamison said Oakmont Council has held several meetings with PennDOT, and there will be many more before a decision is reached about the bridge.

"It's a process, and it's going to take time," Mr. Jamison said, adding that PennDOT has not yet received the funding necessary to build the new bridge -- or tear down the old one.

To read Eric DeLoney's PG article, go to www.post-gazette.com/pg/09186/981650-109.stm.

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