{"nrhp_refnum":"78002142","name":"Twin Arch Stone Culvert","other_names":[],"category":"structure","location":{"address":"N of Troy at SR 25A","address_restricted":false,"city":"Troy","county":"Miami County","state":"OH","lat":40.08796270800008,"lon":-84.22320056599995,"geom_source":"nps_gis"},"listed_date":"1978-07-17","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering","Transportation"],"significance_levels":["local"],"summary":{"what_it_is":"A twin-arch limestone culvert near Troy, Miami County, Ohio, built in 1837 as part of the extension of the Miami Canal. It carried a small ditch beneath the Miami-Erie Canal to the Great Miami River.","why_significant":"The nomination calls it a unique segment of the Ohio canal system and links it to important canal engineers, including Samuel Forrer and David Bates. Only one other similar canal structure, the Turtle Creek Culvert in Shelby County, is known in the state, and it is in an advanced state of disrepair.","narrative":"Near Troy in Miami County, Ohio, a twin-arch limestone culvert once let a small ditch pass beneath the Miami-Erie Canal and drain into the Great Miami River. It was built in 1837 as part of the extension of the original Miami Canal. Each arch has a radius of seven and a half feet and is formed of limestone voussoirs. The structure is 96 feet wide and 35 feet long, with wing walls adding 20 feet. Its foundation was dug under water and rests on rock or on wooden pilings driven to bedrock. Samuel Forrer served as principal engineer on the extension and David Bates as resident engineer. The contract went first to Loring Brownell and Norman Sumner, and John Kleine completed the work using German immigrant laborers. Only one other similar canal structure, the Turtle Creek Culvert in Shelby County, is known in Ohio. The culvert is now abandoned, silted and partly shifted by floods. A road project that threatened it was redesigned to preserve it.","period_of_significance":"1837-1913","architect_builder":"Contract awarded to Loring R. Brownell and Norman Sumner; completed by John Kleine. Principal engineer Samuel Forrer; resident engineer David Bates.","architectural_style":null,"criteria":[],"status_note":"Listed as abandoned and unoccupied, in fair condition; badly silted, with some stones dislodged by river flooding and part of one wing wall slipped out of position.","vacant_flag":true,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:53:10.281162-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_OH/78002142.pdf"},"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71990341","wikipedia":null,"wikidata":null},"indexable":true,"url":"https://nationalhistoricalregister.com/ohio/miami-county/twin-arch-stone-culvert-78002142/"}