Big Cut Road Overpass

Recycled Pratt Pony Truss Overpass over BNSF Railway
Mt. Carroll, Carroll County, Illinois

Click the Photo Above to See All Photos of This Bridge!
Name Big Cut Road Overpass
Built By Chicago, Burlington & Quincy Railroad
Contractor Unknown
Currently Owned By BNSF Railway
Length 193 Feet Total, 73 Foot Main Span
Width 1 Road Lane (Formerly 1 Track)
Height Above Ground 25 Feet (Estimated)
Superstructure Type Pratt Pony Truss and Trestle
Substructure Type Timber Pile
Date Fabricated (Truss) 1872
Date Erected 1906, Approaches Rebuilt 1950
Original Location (Truss) Unknown
Traffic Count 0 Trains/Day (Bridge is a Road)
Current Status Closed to all Traffic
CBQ Bridge Number 137.91
Significance National Significance
Documentation Date April 2019
In 1869, the Chicago and Iowa Railroad began construction on a new mainline, connecting an existing line at Aurora to Rochelle, Illinois.
By 1871, the line would be extended as far as Oregon, Illinois.
In 1885, the Chicago, Burlington & Northern Railroad began construction of a line from La Crosse, Wisconsin to the Illinois/Wisconsin State Line, at East Dubuque.
The line would be extended as far as Oregon, Illinois in 1886, another 85 miles. At Savannah, a line dipped south towards the Quad Cities.
These two lines would be consolidated into the Chicago, Burlington & Quincy in 1899, which began operations of many lines in the area.
This line was one of the most important on the system, as it connected the Twin Cities of Minneapolis and St. Paul with Chicago.
The line was eventually double tracked from Savannah to La Crosse by 1904. It would be finished to the Twin Cities in 1912.

The CB&Q bridge became a part of the Burlington Northern Railway in 1970, after combining with the Great Northern and Northern Pacific Railroads.
The BN merged with Atchison, Topeka & Santa Fe in 1996. This line has become known as the Aurora Subdivision, which is a heavy mainline for BNSF.

Located west of Mt. Carroll, this unique pony truss bridge has been recycled for another use.
Originally built in 1872 as a 5-panel pin connected Pratt Pony Truss railroad bridge at an unknown location, the truss was disassembled and moved here in 1906. Upon reconstruction, it appears that new floor beams were added, likely of scrap components.
Upon relocation, the bridge was set onto timber substructures and approached by trestle. The bridge has served as a road bridge since then, allowing cars to safely cross above the busy mainline below.
Reusing railroad spans for overpasses is not a unique thing. However, over 95% of the original population of railroad bridges reused for road have been replaced.
The truss is extremely significant, due to the old age. It appears some modifications were made to the trusses themselves, but otherwise, they are largely unaltered. It is unknown where the truss came from, but it was likely a heavily constructed railroad span on a mainline.
Unfortunately, it looks like this one might meet the same fate as most others. The road has been closed since at least 2017, due to structural issues throughout the bridge. Unfortunately, the bridge is scheduled for demolition in the early 2020s.
Among the biggest issues is the south approach, which has begun to deteriorate significantly. Holes in the approach pavement indicate the abutment was compromised. The last time the timber components were replaced was in 1950, when both approaches were replaced.
Fortunately, the truss appears to remain in better condition than the rest of the bridge. However, the floorbeams are significantly deteriorated at the connections, although the truss members are not deteriorated. This furthers the evidence that the floorbeams were made of scrap material.
Overall, the bridge remains in a deteriorated and closed condition. While the approaches of the bridge are likely too far gone to be saved, the truss could feasibly be used elsewhere as a driveway or pedestrian bridge with some upgrades.

The author has ranked this bridge as being nationally significant, due to the unique example of a truss reused for road use.
The photo above is an overview.


Source Type


Build Date CB&Q - Allen Moore collection - BRHS Archives
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele

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