Fall in Love with a Metal Truss Bridge

My undistinguished career as a columnist began with an article entitled “The Chartiers Street Bridge” that I submitted to the Almanac in November, 1993, lamenting the imminent demise of the bridge carrying Chartiers Street over the railroad in Bridgeville. Marsha Maddy, wife of my nephew Jonathan, was so impressed with the fact that they had actually published it that she encouraged me to write a weekly column and find someone to publish it. Sure enough, the Bridgeville Area News took me up on the offer, and “Water Under the Bridge” was launched.

The column had a nice run until March 2020 when Gateway Publications advised its free-lance “stringers” that their services would no longer be required; publication of The Signal-Item was temporarily suspended because of financial problems attributed to the Covid-19 pandemic. The newspaper resumed publication a few months later; the termination of the stringers was not temporary; and “Water Under the Bridge” morphed into a Blog.

The original article acknowledged that it was necessary to replace the one lane bridge with something more practical, but wished that it had been possible to relocate this historic artifact to another site. This, of course, did not occur, and the Chartiers Street bridge was reduced to scrap, re-melted, and resurrected as beer cans.

Twenty-eight years later someone sent me a newspaper article reporting that PennDOT was in the process of dismantling the historic one-lane through truss Kelly Road bridge built in 1897 over the Shenango River in Mercer County and that “through a partnership with the Department of Conservation and Natural Resources, the bridge will be refurbished and relocated to Pymatuning State Park next year as part of the bike trail system.”

This exactly what I had advocated in 1993 – what a treat it was to learn that someone else had the same idea! And the more I read, the better the story got. Turns out this was the second time in less than a year that PennDOT District One had salvaged and repurposed an old metal truss bridge. Last July the Messerall Truss Bridge in Crawford County was relocated to Pymatuning, all in one piece. Constructed in 1876 over Pine Creek in Oil Creek Township, it had been out of service since 1987. In its new life it will carry a multi-use trail over Linesville Creek.

Even better was my learning that PennDOT has a formal Historic Bridge Management Plan and that they are working with the Pennsylvania State Historic Preservation Office and the Federal Highway Administration “to take sensible measures to extend the useful life of historic truss bridges” and “in cases where important bridges cannot be rehabilitated to meet a transportation need, but can be moved, …. to encourage their adaptive reuse at another location for alternative uses such as pedestrian or bike traffic”. That sounds like something I would have written.

According to this plan, there were 851 metal truss bridges in Pennsylvania in 2001; the number had shrunk to 414 by 2018. Obviously very few of these can be rehabilitated sufficiently to meet contemporary requirements, but many of them could be moved and repurposed, particularly in an era when the construction of hiking/biking trails is booming. The Management Plan outlines a program to identify all the historic (pre-1900) bridges still in existence and prioritize them to ensure that a maximum of different designs survive in every part of the state.

In addition, PennDOT is charged with the responsibility of identifying alternative uses for bridges that must be replaced. One hopes that that responsibility is discharged as conscientiously in all the PennDOT Districts as it has been in District One. The legal basis for this program is Section 106 of the National Historic Preservation Act, which was passed in 1966.

The rationale for this concept was eloquently articulated by Tyra Guyton, Transportation Special Initiatives Coordinator for the Pennsylvania State Historic Preservation Office, in an article entitled “Fall in Love with a Metal Bridge”. In it she sings the praises of the elegant remnants of a long past technology and records her fascination with them, while pleading with her readers to help preserve them.

My Almanac article combined some wistful sociological comments on the Chartiers Street bridge and its position in Bridgeville’s historical legacy with a brief critique of the ingenious design concepts it records. Indeed, the evolution of the technology used to produce our beloved covered bridges into the design philosophy that was developed to utilize the versatility of wrought iron is remarkable.

Each remaining wrought iron bridge is an independent museum filled with examples of the introduction of the basic principles of solid mechanics into structural engineering. Need an example of a simple tension member? Look closely at the pin-connected lower chord eyebars. Want to explain the concept of (Euler) column bucking? Carefully examine the boxed channel compression members. Etc. Etc. Etc. The campus of every university with a respectable Civil Engineering program needs one of these artifacts as a teaching aid.

My current local favorite old truss bridge is the one carrying the railroad across the old Chartiers Creek channel five hundred yards north of the Bridgeville History Center. Reduced to a single track and carrying three trains a week each way, its workload is a fraction of what it handled a century ago. Even the stream it crosses has been diverted, leaving only the trickle supplied by McLaughlin Run underneath it. Nonetheless it proudly stands its ground, awaiting a visit from the next curious bridge-hunter. I should forward my photographs of it to Ms. Guyton.

We preservationists are champions of lost causes with far too many failures and far too few victories. Learning that PennDOT is now officially on our side must be counted an excellent victory.

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