US-12 St. Joseph River Bridge

Information and Findings From Michigan Historic Bridge Inventory

Narrative Description

The five-span US-12 Bridge consists of two identical side-by-side superstructures, one carrying the eastbound lanes and one for the westbound lanes. A narrow gap separates the structures. East side has two variable-depth deck plate girders with four steel I-beam floor beams per span. The center 101-foot span is flanked by 100-foot spans; the outer spans are 89.5 feet. Four steel I-beam stringers extend between each pair of floor beams. A series of back-to-back angles serves as bridging between the girders, below the floor beams. Three-and-one-half-foot-wide sections of concrete, supported by brackets made of angle braces and plates, are cantilevered beyond the girders. These projecting sections support the curbs and sidewalks on the outside, and the median in the middle, of the deck. Standard-design metal railings and posts edge the outside of the sidewalks. The bridge is supported by H-shaped concrete piers and by concrete stub abutments with U-shaped concrete wing walls. Bridge plates are affixed at the northeast and southwest corners.

The bridge was built in 1954 as part of the relocation of M-60, now US-12, south of Niles. The contractor for the $634,107.84 federal-aid project, L.W. Lamb of Holland and Jackson, had been in business since at least the 1930s, and had erected a number of bridges in Michigan. One of the 65 highway river crossings planned by the state highway department during the 1953-54 biennium, the US-12 Bridge followed the department's practice of including divider strips between opposing lanes of traffic on dual-lane highways, and using "separate structures carrying each roadway...where roadways are widely separated."

This project also reflected the department's push to construct urban by-passes on the seven routes in Michigan included in the 37,681-mile system authorized by the U.S. Public Works Administration in 1947. Work began at Jackson and Flint during 1951-1952. The Niles by-pass joined similar projects in Ann Arbor, Muskegon, Holland, Kalamazoo, Michigan (I-94) and South Bend, Indiana (I-80 and I-90).