{"nrhp_refnum":"88000868","name":"Bridge in South Beaver Township","other_names":[],"category":"structure","location":{"address":"Walts Mill Rd. over Little Beaver","address_restricted":false,"city":"Cannelton","county":"Beaver County","state":"PA","lat":40.79152101300008,"lon":-80.49166100999997,"geom_source":"nps_gis"},"listed_date":"1988-06-22","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A steel Pratt pony truss highway bridge over Little Beaver Creek on Walts Mill Road in South Beaver Township, Beaver County, near Cannelton and New Brighton, Pennsylvania. It was built about 1878 by the West Penn Bridge Company.","why_significant":"The bridge is an unusually configured pin-connected Pratt pony truss. It looks like a typical simply supported pony truss from the roadway, but a central pier makes it function as a continuous two-span bridge, which is unusual for this truss type. It is one of seven Pratt pony truss bridges included in the nomination, with construction dates from 1871 to 1906.","narrative":"Built about 1878 by the West Penn Bridge Company, this steel Pratt pony truss carries vehicles over Little Beaver Creek on Walts Mill Road in South Beaver Township, Beaver County. Its two spans total 109 feet overall, with a main span of 48 feet, and the truss is pin-connected with loop-welded or die-forged eyebars. From the roadway it appears to be an ordinary simply supported pony truss, but a single central stone pier supports it, so it works as a continuous two-span bridge. Most pony trusses rest only at each end, making this arrangement unusual in both its function and its substructure. The nomination places it in the engineering field as one of seven Pratt pony trusses assessed together, a group built between 1871 and 1906 in several parts of the state. Its original wood deck was later replaced with an open steel grid, and the bridge was reconstructed in 1976.","period_of_significance":"c. 1878","architect_builder":null,"architectural_style":null,"criteria":["C"],"status_note":"Wood deck replaced with open grid; guardrail replaced; deck rivets replaced with bolts in places; reconstructed 1976.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:37.720271-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000868.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000868/9783298c0c-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000868/9783298c0c-1600.webp","licence":"Public domain","author":"Mvincec","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Watts_Mill_Bridge1.JPG\" rel=\"noopener\">Mvincec</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Watts_Mill_Bridge1.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71992270","wikipedia":"https://en.wikipedia.org/wiki/Watts_Mill_Bridge","wikidata":"https://www.wikidata.org/wiki/Q7975033"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/beaver-county/bridge-in-south-beaver-township-88000868/"}