|30 Mile Bridge Trio||
Truss and Beam
|30 Mile Road||Macomb County, MI||Rural||Clinton River and Branches|
This is a section of abandoned road (see the map for more info) that can take a person back in time and reveal what a drive in the 1920s might have been like. Three historic bridges used to carry 30 Mile Road over the Clinton River and a couple small branches. Starting from the East, you would cross a small steel stringer beam bridge with lattice guardrails. You would then cross a slightly larger beam bridge (which I call the Middle Bridge), which would also have lattice guardrails, but they would be a bit taller. Finally, you would cross the Clinton River, on a pin connected Pratt pony truss. The Michigan Historic Bridge Inventory mentions all three of these bridges, and gives a date of 1920 for the construction of all three bridges.
Today, the first small beam bridge (from the East) is the only one whose deck still stands. This was a standard plan steel stringer beam bridge, with standard lattice guardrails. This particular design of bridge appeared to have a guardrail problem, since most of these bridges, including this 30 Mile Road example, have guardrails that are falling off the bridge. It appears to be the way in which the guardrails were held on the bridge via a brace... when the brace rusted, the guardrails would fall off. Cobblestone abutments are present, however these have been completely covered in concrete.
The second, middle bridge, is also a beam bridge with lattice guardrails, however the guardrails are taller, and mounted differently. I would not place this bridge in the standard plan category that I put the first beam bridge in. This bridge's fate was exactly the opposite as the first bridge - the deck has collapsed, but the guardrails have survived, mounted into the abutments at each end! The collapse of this bridge appears to have involved the concrete covered cobblestone abutments. Along with the deck, that appeared to break in the middle, the cobblestone abutments are tipping over at one end. Flood waters appear to have helped to wash the abutments free, which resulted in them tipping over.
The truss bridge, which crosses the main Clinton River, appears to have been a pin connected Pratt pony truss. It sat on concrete abutments, that may also have cobblestones behind them. Like the middle beam bridge, the deck appears to have broke in the middle. The abutments seemed intact from what I could see at the east side of the bridge. I could not cross the river, and did not inspect the west side when I visited. All of these bridge appear to have been collapsed for some time, yet many parts of this bridge remained in the water when I visited. Eye bars, turnbuckles, members and even the top chords are still here.