Bridge L5853 pedestrian bridge over streetcar right-of-way
Bridge number: L5853
Year built: 1904
Engineer: William S. Hewett
Contractor: William S. Hewett & Company, Minneapolis
Overall length: 88 feet
Overall width: 17.5 feet
Adapted from the National Register of Historic Places nomination form prepared by Robert M. Frame III. Bridge No. L-5853 was listed on the National Register of Historic Places in 1989.
Bridge No. L-5853 spans an abandoned, east-west, street railway right-of-way located within the boundaries of Como Park, northwest of downtown St. Paul, Minnesota. The bridge is a short distance north of east-west Horton Avenue, which is the southern boundary of the south central part of the park. Como Park is the city's major urban park and was designed in the 19th century to encompass the wooded and grassy rolling hills around Lake Como.
Bridge No. L-5853 is a three-span, open-spandrel, reinforced concrete, barrel-arch bridge. It has an overall structure length of 88 feet, with a clear main-span arch of 50 feet and flanking slab spans of 12 feet each. The out-out width is 17.5 feet, carrying a pedestrian walkway of 15 feet. The rise is 12.5 feet. The slab floor is carried by skew-back piers and the center portion of the arch ring. The flanking approaches span the spaces between the piers and abutments. The reinforcement of Bridge No. L-5853 consists of five latticed Melan ribs in the arch ring and Thacher bars in the skewback piers and floor slabs. In the floor slabs, 3/4-inch bars parallel to the bridge axis are placed 7 1/2 inches apart on the tension side. The bars in the piers are of the same diameter and have the same spacing, but are set vertically and on both sides of the pier. The floor slab retains the original cornice molding and the end posts, but the open-balustrade railing with separately cast, round balusters, intermediate posts and hand-rails are gone. Remnants of suspension brackets for the street railway catenary cables are attached to the arch soffit. The bridge has suffered some spalling, but the significant Melan-reinforced concrete arch retains full integrity.
Architecturally, the bridge is designed in the Classical Revival style, as embodied largely in the railings. A description of the bridge in Fourteen Annual Report 1904 of the St. Paul Board of Park Commissioners says that it was "moulded into forms of architectural elegance." A notable feature in the surface finish of the concrete. In order to avoid form marks on the exposed surfaces the forms were covered with patent wood laths, consisting of boards with parallel dove-tail grooves and ribs, which were plastered with a coat of cement mortar finished smooth. Before pouring the concrete the plaster lining was coated with boiled linseed oil. This expensive lining was used on all exposed surfaces, including the soffit of the arch.
Bridge No. L-5853 is historically significant as an outstanding, virtually unaltered, extremely early example of a reinforced concrete arch bridge in Minnesota. Built in 1904, along with Bridge No. 92247, it is the second oldest known extant reinforced concrete arch bridge with documented construction dates in Minnesota. This bridge is also significant for employing the patented Melan reinforcing system. Finally, it is significant as the work of noted Minneapolis bridge builder, William S. Hewett.
The I-beam, arch-reinforcing-system invented by the Viennese engineer Josef Melan, was patented in the United States in 1894. The first Melan-system bridge was built in Rock Rapids, Iowa, that same year by William S. Hewett & Company of Minneapolis. Ten years later, William S. Hewett and Company was the contractor for Bridge No. L-5853 in Como Park.
According to the Twelfth Annual Report 1902 of the St. Paul Board of Park Commissioners, the St. Paul City Railway (part of the Twin City Rapid Transit Company) was permitted to reroute and double the Como Park single track of its Como-Harriet streetcar line, with the provision that "its tracks were not to cross any permanent park Road at the surface, but were to run under or over bridges constructed by the Company." The surviving single drawing for Bridge L-5853 is undated, but does indicate that it was prepared by William S. Hewett and Company using "System Melan Concrete-Steel Construction."
During 1904 the street railway had designed and built two bridges in compliance with the policy. Bridge No. 92247 was built to carry Lexington Avenue over the tracks and Bridge No. L-5853 was built to provide a pedestrian crossing for passengers at the new station to be built the next year at the bridges southeast corner. The siting of the bridges was significant not only because of the location of the railway and station, but also because the city was developing this area at Lexington Parkway as a new and improved park entrance. By the end of 1906, as reported in the Sixteenth Annual Report 1906, the Board of Park Commissioners reported that "this beautiful section of the Park, heretofore isolated and neglected . . . because the Public could not reach it through any convenient and improved pleasure drive, is now brought into prominence and [a] stream of…people [is now] using Lexington Parkway as a pleasure way for reaching the Park..."
Contractor William S. Hewett is historically significant as a major Minneapolis bridge builder from the 1890s until well into the 20th century. He is also significant for his pioneering work in reinforced and pre-stressed concrete. Hewett probably became familiar with the Melan reinforcing system when he built the first American Melan bridge while he was doing general bridge construction in northwest Iowa. At the time he was an agent for his uncle, Seth M. Hewett. In 1899, he formed his own William S. Hewett and Company, specializing in reinforced concrete bridges and it was this firm that built Bridge No. 92247 and Bridge No. L-5853 in St. Paul in 1904. In 1907, he formed the Security Bridge Company, and in 1913, Hewett Systems, after which he focused on the development of pre-stressed concrete.