Bridge built before the automobile age sparks talk of preservation for its history, condition, age
Thursday, April 19, 2007
By Carole Gilbert Brown
Pittsburgh Post Gazette Wire
The single-lane, single-span Dorrington Road Bridge crossing the rushing waters of Robinson Run in Collier rates highly with bridge experts and history lovers for its design, condition and age.
But those are the factors that have placed the 119-year-old span on the endangered list.
The state Department of Transportation wants to replace the 60-foot-long bridge, which is 19 feet wide, with a concrete box-beam bridge that would be wider for two traffic lanes, would have expanded approaches for improved sight distance and would be have a stronger structure that would remove the current nine-ton weight restriction.
PennDOT wants to demolish the bridge and erect its replacement within two years.
PennDOT, the Pittsburgh History & Landmarks Foundation and Collier officials met last month to discuss relocating the structure, which is eligible for national historical registry designation, to an undeveloped 50-acre park near Nevillewood, where it could be situated over a gully near the old Woodville cemetery.
Several other township sites are potential relocation places, too, including on the Panhandle Trail.
“It would be most appropriate to keep the bridge in Collier, but it could go elsewhere,” said Louise Sturgess, Pittsburgh History & Landmarks Foundation executive director, who believes retention of the structure is necessary to show the evolution of bridge design science during the 1800s.
Retaining the structure locally is important to the region, too, because of Pittsburgh’s designation as “the city of bridges,” she said.
Mrs. Sturgess has enlisted the aid of Todd Wilson, a 2006 civil engineering graduate of Carnegie Mellon University and a bridge enthusiast since childhood, to develop cost estimates.
Mr. Wilson, a traffic engineer for DMJM Harris who has a copy of the original drawings for the bridge, believes the structure could be a tourist attraction, even on a national level. He also sees it as an educational tool and a community landmark.
What makes the pin-connected Pratt pony truss bridge, built in 1888 by the Pittsburgh Bridge Co., unique is its basic design and vertical end posts, which are now covered by black-and-yellow road markers.
In most standard truss bridges, the end posts are inclined. The use of vertical end posts is more typical of earlier 19th-century designs which went by the wayside because they used more material and, thus, were more expensive.
Another unusual characteristic is that the bridge is made partially of cast iron instead of steel.
“It’s the oldest metal truss bridge that is unaltered and still open to traffic,” Mr. Wilson said. “The Dorrington Road Bridge represents an archaic design, even for 1888. Though Allegheny County once had several similar bridges, they have all been demolished.
“If any bridge is saveable and worth saving, it is this one,” he said.
Wherever the bridge ends up, it’s clear that funding will be needed.
Mrs. Sturgess indicated the foundation could apply for a History Channel grant, as well as coordinate fund-raising campaigns.
“I really see this as a wonderful community project,” she said, pointing out that university students as well as Chartiers Valley students could get involved.
Mr. Wilson said professors from Carnegie Mellon and the University of Pittsburgh had expressed interest in supplying students for the relocation project.
In last month’s meeting with PennDOT, the history foundation and Collier, Mr. Wilson ended his presentation with these words, “The Dorrington Road Bridge has served Collier Township for over five generations. Dating from a time before the automobile was invented, it is a rare surviving piece of transportation history. By relocating the bridge to a park or trail, we can preserve this structure and create a ‘bridge’ to the past for many more generations to enjoy.”
The Dorrington Road Bridge is featured on the Web site, www.historicbridges.org.