Amtrak/PRR 1888 Bridge over Conestoga Creek in Lancaster, PA

(Bridge Hunter; HAER; 3D Satellite) Historic Bridges has a lot of bridges in Lancaster County, but not this one.

This is one of  the first multiple-arch bridges designed by William H. Brown, the Chief Engineer of the Pennsy Railroad. The Rockville Bridge is a good example of one of his later designs.

(Update: Michael Fioio's blog provides some history about William Brown, this bridge and the Conemaugh Bridge.)

This side looks "rough" because the bridge was built for just two tracks with the intention of adding two more tracks. So the stones are staggered so that the anticipated new construction could key in with the existing structure.

Photo from HAER PA,36-LANC,10--3 from pa3740
Perspective view of downstream elevation, looking due east. - Pennsylvania Railroad, Conestoga Creek Viaduct, Spanning Conestoga River, South of City Water Works, Lancaster, Lancaster County, PA

William Brown used stone instead of iron because of a suggestion by Pittsburgh Division Superintendent Robert Pitcairn. Only two tracks were built at the time because they decided to use "Gallitzin stone," a sandstone from the Allegheny Mountains, for better durability. To offset the increased transportation costs of that stone, they reduced the width to two tracks.  [HAER-data]

Photo from HAER PA,36-LANC,10--1 from pa3740
Upstream elevation, looking south. - Pennsylvania Railroad, Conestoga Creek Viaduct, Spanning Conestoga River, South of City Water Works, Lancaster, Lancaster County, PA

The original bridge was built as part of the Pennsylvania canal system by the state-owned Columbia & Philadelphia Railroad. The 1829 bridge consisted of eleven wooden Town lattice trusses on stone piers for a total length of 1,412'. The PRR acquired the troubled canal system in 1857. In 1863 they "filled the approaches, reducing the viaduct's length to 349', and replaced the spans with a series of iron Whipple trusses." They must have needed a stronger bridge to carry Civil War supply trains because one seldom sees railroad upgrades done during the Civil War because the North would be spending railroad construction resources repairing tracks damaged down south by the Confederates. In 1886, the PRR began another round of main-line improvements. Foundations were laid for four tracks, but the width was never increased. The four-track main line from Philadelphia to Harrisburg was completed in 1900, but two of the stone bridges, Lancaster and Coatesville, had just two tracks. "Perhaps the PRR was then already planning a low-grade freight bypass, constructed from 1902 to 1905, which reduced traffic on the main line." [HAER-data]

Gregory D. Pawelski posted three photos with the comment: "Pennsylvania Railroad Conestoga River Bridge in Lancaster, Pa. - Then, Then and Now."

1
Pennsylvania Railroad Conestoga River Bridge in Lancaster, Pa. circa 1870-1880. (William T. Purviance Photo New York Public Library)
Robert Wanner Wasn't built to support heavier Main Line trains, soon replaced.

2
Pennsylvania Railroad Conestoga River Bridge in Lancaster, Pa. circa 1900. (Fred J. Moll Collection)
Robert Wanner Adequate construction that is still there in 2018.

3
Pennsylvania Railroad Conestoga River Bridge in Lancaster, Pa. in July 2011. (Google Image Capture)

Harold Castleman commented on Gregory's post
Here's GG-1 No. 4877 leading an excursion over the Conestoga River circa 1980.

The north side was finished with a weather-resistant facing. But the south side was intended to be inside a four-track bridge and thus protected from the weather. Since it was not protected, in 1930, Belmont Iron Works added bracing to tie the spandrel walls together. [HAER-data]

MichaelFroio, comments in source talk about Cambria Iron Works
In a beautiful image by William H. Rau we see the Conestoga River bridge, one of Brown's first stone bridges. Utilizing the figure and boat as a device for scale in the foreground Rau is looking south, as noted by the finished facade of the bridge. To the left out of view is the Lancaster Water Works which still survives today. Photograph collection American Premier Underwriters, Inc

Ray Brunner posted
PRR main line bridge over the Conestoga Creek, Lancaster Pennsylvania. Photo by A. J. Brunner c1940