This bridge is one of only a couple known examples in North America of a Rainbow Arch bridge with diagonals, making the bridge difficult to classify because it might also be considered a concrete truss. This bridge, along with a similar replaced bridge that was also in Lancaster County, as well as a similar bridge located in Mississauga, Ontario are sometimes called concrete truss bridges and are sometimes called concrete arch bridges. Indeed, the HAER documentation for this bridge describes the bridge as a concrete arch, while one of the measured drawings labels it as a truss. In reality, perhaps this bridge can be compared to metal bowstring truss bridges of the 1870s, which have characteristics of both arch bridges and truss bridges. The fact that Rainbow Arch bridges are often called concrete bowstring arch bridges seems to support this comparison. HistoricBridges.org has classified thecWeaverland Bridge on the website as an arch for the same reason that many metal bowstrings are classified on this website as truss bridges: because based on the stylistic appearance of the bridge, this is where the lineage of the structure lies. This bridge has so much in common with a rainbow arch, that it makes sense to list the bridge as an arch.
The Weaverland Bridge is not a Marsh Arch, and was instead designed by local engineers in Lancaster County who had a profound effect on bridge construction in Lancaster County by strongly promoting the construction of concrete bridges (particularly concrete girders) in the county during the first couple decades of the 20th Century. Enough of these bridges were built, and of high quality as well, that Lancaster County has more concrete girders than other counties in Pennsylvania even today. The Weaverland Bridge represents one of the more unusual concrete bridges that was designed and built in the county.
This bridge's near twin on Auction Road, which was essentially identical except that it lacked a t-beam approach span, was replaced several years ago. The replacement bridge was intended to be replica of the historic bridge, and as modern bridges go, it actually is a pretty good rendition of the historic bridge, which is suprising. HistoricBridges.org does not consider the complete demolition and replacement of a superstructure to be a form of historic preservation, and will not attempt to classify this project as preservation. And given the extreme rarity of this design (even if Lancaster County happened to have two examples) every effort should have been made to avoid the demolition of the historic bridge, even if it meant bypassing and abandoning the bridge. However, ignoring the devastating loss caused by the demolition of the historic bridge, it is still worth noting that in terms of mitigation for the adverse effect of demolishing the historic bridge however, the project is a good example of how Section 106 process might be resolved in the spirit of the law, because the replacement bridge does have the likeness of the historic bridge. Other projects in other states and counties have attempted to "replicate" historic bridges and they usually fail horribly (yet are still approved as Section 106 mitigation), so the Auction Road Bridge project is noteworthy as an exception to the norm. A PDF describing the project is available at the top of this page.
That said, because the Auction Road Bridge was demolished, the only acceptable option for the Weaverland Bridge is the preservation of the existing structure and materials. With an ADT of 175, and some of the local population being Amish and not even using motorized vehicles, there is no reason to not preserve this bridge for continued use. Spalling on the bridge should be repaired, and the entire bridge might be coated with a sealant to prevent future spalling and deterioration.
Information and Findings From Pennsylvania's Historic Bridge Inventory
Discussion of Bridge
The tied thru arch bridge built in 1916 has been determined eligible by PHMC (5/24/93). It is an early and rare example of its type/design in the state.
Discussion of Surrounding Area
The bridge carries a road over a stream in a rural setting with an active limestone quarry to it south and very altered late 19th century vernacular residence to its north. The setting does not appear to have historic district potential.
Discussion of Replaced, Nearly Identical Bridge On Auction Road
The single span, 58'-long, tied thru arch bridge built in 1922 is supported on concrete abutments with U-shaped wingwalls topped by plain concrete parapets. The arch consists of two parallel ribs, vertical suspenders, and a concrete slab deck. Uncommon details with this example are the diagonal members and the lack of clearly defined tie girders. Without the plans, it is not possible to tell whether this is a true reinforced concrete thru arch or an encased steel thru arch, but nevertheless the design is unusual. It is one of two similar examples with the diagonal members in Lancaster County (BMS# 36 7213 0894 4002). The tied thru arch type/design was introduced in the United States after 1905 with the best known variation a patented design by James B. Marsh of Des Moines, Iowa. The bridge is the latest of 7 reinforced concrete thru arch bridges in Pennsylvania from 1907 to 1922. It is historically and technologically significant as a rare example of its type/design.
Bridge Considered Historic By Survey: Yes
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