Bridge 92247 on Lexington Ave over streetcar right-of-way
Bridge number: 92247
Year built: 1904
Engineer: William S. Hewett
Contractor: William S. Hewett & Company, Minneapolis
Overall length: 47 feet
Overall width: 53 feet
Adapted from the National Register of Historic Places nomination form prepared by Robert M. Frame III. Bridge No. 92247 was listed on the National Register of Historic Places in 1989.
Bridge No. 92247 carries Lexington Avenue over an abandoned, east-west street railway right-of-way. The bridge is located within the boundaries of Como Park, northwest of downtown St. Paul, Minnesota. It 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. 92247 is a single-span, filled-spandrel, three-center-curve-intrados arch bridge, with an overall structure length of 53 feet, a clear span of 38 feet, with an out-out width of 53 feet. The bridge carries a 36.4-foot roadway, with two 7-foot sidewalks. The rise is about 7.5 feet, with a vertical clearance beneath the arch soffit of 16 feet. The U-abutments are integral with the spandrel walls and the arch is made monolithic with the abutment walls. The bridge is reinforced with 16 segmental I-beam Melan ribs, 5 inches deep and 38 inches apart on centers. The ends of the I-beams rest on 2-inch by 2-inch horizontal transverse angles embedded in the abutment concrete. There webs are connected by horizontal tie rods. All the exposed concrete surfaces, except the arch soffit, is faced with random-coursed ashlar Kettle River sandstone, including the abutment face beneath the spring line. The coping has a bush-hammered surface. Overall, the stylistic treatment and form is Classical Revival
Bridge No. 92247 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. L-5853, 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. 92247 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 plans for Bridge No. 92247 were prepared December 19, 1902, and the section drawing indicates Melan reinforcement.
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.