{'fraction_non_alphanumeric': 0.0191625266146203, 'fraction_numerical': 0.0028388928317956, 'mean_word_length': 5.588785046728972, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Overview of the National Historic Covered Bridge Preservation (NHCBP) Program

Covered wooden bridges proliferated in the United States in the mid-nineteenth century. Today an estimated 800 covered bridge structures remain, but they are nevertheless cherished links to the technological heritage of the United States. The through-truss designs vary from the Kingpost trusses built in the craft tradition to the engineered Burr arch and Paddleford trusses. Covered bridges are our links to the past and the pioneering bridge-building efforts, and as such, are considered important early American transportation structures to preserve for posterity. This paper provides an update on the National Historic Covered Bridge Preservation (NHCBP) Research Program sponsored by the Federal Highway Administration (FHWA). An overview of the National Program is included along with an update of the latest research activities funded by the recent SAFETEA-LU legislation over the past 3 years. The NHCBP program provides funds to support preservation/restoration efforts for covered bridges that are listed, or are eligible for listing, on the National Register of Historic Places. Program funds also support research and technology transfer activities for restoring, preserving, and protecting covered bridges, including an educational component to disseminate information as a means of preserving our cultural heritage.