Ford Exit Dr. / US-12County: Washtenaw
City/Township: Ypsilanti Twp.
Location: Ford Exit Dr. / US-12
Year Built: 1942 About this Bridge: The four bridges comprising the Willow Run Tri-level Grade Separation Historic District are eligible for the National Register as significant components of the expressway system developed during World War II to serve the Willow Run bomber plant. The B-24 aircraft produced at the facility were considered vital to the nation's defense. The bridges are also eligible under the category of Engineering as a creative solution to the massive volume of traffic anticipated when shifts changed at the bomber plant. The tri-level grade separations are located on a section of US-12 developed during World War II as the Willow Run Expressway. The 21-mile-long divided highway edged the Willow Run bomber plant to the north, west, and south. To the east, it merged with the 17-mile Detroit Industrial Expressway, which was also under construction during the same period. Designed to produce the massive B-24 bombers, the $47 million Willow Run plant included "its own airport, hangars, assembly building nearly a mile long, machine shop, power plant and offices." When the Ford Motor Company unveiled plans for the facility in February 1941, Michigan's highway department was confronted with a significant problem: "Here was the world's largest plant under one roof located more than 20 miles from its main source of labor." The Willow Run work force was projected to reach 100,000, mostly to be drawn from Detroit. Employee transportation was not the only logistical quandary confronting planners. A highway department survey in 1941 found that thirteen percent of Michigan's factories received all production materials by truck; over half relied on trucks to ship their finished product.