14th. St. / M-54 (Saginaw St.)
Location: 14th. St. / M-54 (Saginaw St.)
Year Built: 1941
About this Bridge:
The Saginaw Street Underpasses are a pair of identical structures – one now open, one closed – that carry Fourteenth Street and an abandoned line of the Grand Trunk Western Railroad over Saginaw Street (M-54 BR) in central Flint. Each overpass has four concrete spans, the longest of which extends 38 feet.
The original highway overpass (now closed) is configured as a T-beam structure, with relatively shallow girders braced by solid concrete diaphragms. The railroad structure (now carrying Fourteenth Street) “is of unique design,” as described by MSHD, “consisting of a heavily reinforced concrete slab which supports the railroad tracks on rubber pads without the use of ties or ballast.” Both structures are supported by concrete abutments and spill-through piers. The abutments and piers provide much of the bridges architectural expression, with their Art Moderne concrete corbeling and scored vertical lines. The asphalt-paved concrete roadways on both are flanked by concrete sidewalks, which are in turn bounded by MSHD standard, ornamental steel guardrails with paneled concrete posts. The guardrail extends continuously between the two overpasses to join them on both sides of the highway. It si used on the concrete stairs between the two structures that extend down the hillsides from the Fourteenth street level to Saginaw Street. In excellent physical condition, both parts of the Saginaw Street Underpass are unaltered other than the removal of railroad rails from the slab structure.
The Saginaw Street Underpasses were designed in 1941 by the Michigan State Highway Department as part of war-related reconstruction of Saginaw Street through Flint. For this crossing, the highway department delineated two structures that appeared almost identical but in reality used entirely different superstructural systems. The original Fourteenth Street span employed an MSHD-standard T-beam superstructure; the Grand Trunk Wester Railroad span used a massive concrete slab, with rubber dampeners to isolate train vibration from the substructure. “This design was especially chosen for this location,” MSHD explained in its Nineteenth Biennial Report, “because its shallow depth permitted the separation of grades without the necessity of raising the tracks to an excessive height or of depressing the streetway to a point where pumping would be required to drain the under-pass area.” The highway department pushed construction of the highway and its related structures through 1941, finishing them before July 1942. After their opening, MSHD stated: “Completion of this project was particularly important since it removed a serious hazard which existed at the old railroad intersection and, in addition, relieved a condition of extreme traffic congestion.
This state highway urban-business route now has divided roadways throughout the length of the project.” The new route would provide improved access to the Fisher Body Plant, then engaged in wartime production. Built as an integral part of one of the state’s most important WWII urban projects outside of the Detroit are, the Saginaw Street Underpasses are historically significant for their role in this pivotal period of Michigan transportation history.