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| Name | East Dubuque Railroad Tunnel |
| Built By | Dunleith and Dubuque Bridge Company (Illinois Central Railroad Subsidiary) |
| Currently Owned By | Canadian National Railway |
| Superstructure Contractor | Saulpaugh & Company of Rock Island, Illinois |
| Length | 851 Feet |
| Width | 1 Track |
| Height Above Ground | 20 Feet (Estimated) |
| Superstructure Design | Bored Tunnel (Concrete East Portal, Exposed Rock West Portal) |
| Substructure Design | Stone Masonry |
| Date Built | 1868-1872 |
| Traffic Count | 10 Trains/Day (Estimated) |
| Current Status | In Use |
| Significance | Moderate Significance |
| Documentation Date | 4/16/2022 |
In 1851, the State of Illinois authorized the construction of a series
of railroad lines, extending from Cairo, Illinois; located on the Ohio
River, to the Mississippi River at East Dubuque, Illinois and to
Chicago, Illinois. The State awarded the Illinois Central Railroad (IC) with the land necessary
to construct the new lines. Surveys began in 1851, and the first
segments were completed by 1853. The northwestern section connected Freeport, Illinois to East Dubuque, Illinois. Construction was completed on this segment in 1855, and the line would later be extended across Iowa with a bridge over the Mississippi River to Dubuque in 1868. In 1890, the Chicago, Madison & Northern Railroad (CM&N), a subsidiary of the IC, constructed 102 miles of new railroad between Chicago and Freeport, Illinois; linking Chicago with the IC lines in northern Illinois. This served as an important connection for the IC, improving access to Chicago for the railroad. Due to heavy use, the section from Chicago to Broadview would be double tracked by 1895. The CM&N would be operated under lease by the IC until 1903, when it was consolidated into the IC. In the 20th Century, the IC was a respected railroad, operating an extensive railroad network through the central United States. This line served as a mainline for the IC, connecting lines in Iowa to Chicago. In 1972, the IC merged with the Gulf, Mobile & Ohio Railroad
(GM&O) to form the Illinois Central Gulf (ICG). This line, as well as the entire IC system in Iowa, was sold to the Chicago Central & Pacific Railroad (CC&P) in 1995. In 1988, the ICG
was reorganized as the Illinois Central Railroad (IC). In 1995, the CC&P was repurchased by IC and in 1998, IC was
purchased by the Canadian National Railway (CN). Today, CN operates the Freeport Subdivision between Broadview and Freeport, and the portion between Freeport and Dubuque is part of the Dubuque Subdivision.
Located immediately east of the Dubuque Railroad Bridge, this tunnel carries the former Illinois Central Railroad under a bluff along the Mississippi River. During the initial surveys of the Dunleith and Dubuque Bridge Company, the railroad was presented with a unique challenge. When the IC initially built into Dunleith (now East Dubuque), the route followed along the Mississippi River. A towering bluff along the east bank of the Mississippi River prevented the railroad from making the necessary curve to cross the Mississippi River into Dubuque at an angle perpendicular to the river. In response, the Dunleith and Dubuque Bridge Company decided to construct a tunnel through the limestone bluff, which allowed the railroad to construct a sharp curve on the approach to the bridge. Work on the tunnel began in 1868, and some sources indicate the tunnel was not completed until 1872. The tunnel would be constructed by Saulpaugh & Company, which also had the contract for the stone piers of the adjacent Mississippi River Bridge.
Currently, the tunnel consists of a 851-foot structure cut through the limestone bluff. The west portal of the bridge has not been improved, and consists of an exposed rock face. At the west end of the tunnel, the railroad crosses the former Chicago, Burlington & Quincy Railroad mainline, now a busy BNSF Railway line. The east portal of the tunnel consists of a concrete and brick arch, set onto stone wing walls. It is believed that this portal was constructed in approximately 1899, when the Mississippi River bridge was reconstructed. It is unknown if this work was completed by contract or by railroad company forces. The tunnel runs at a nearly 90-degree angle, and is set onto a 625-foot radius curve. The only major alteration to the tunnel was completed in the summer of 1953, and consisted trimming the edges of the tunnel, and installing concrete slabs on the roof. Overall, the tunnel appears to be in fair to good condition, with no significant deterioration noted. The author has ranked the tunnel as being moderately significant, as it is the only active railroad tunnel in northwest Illinois.
Citations
| Builder and build date | Illinois Central Magazine; 1957 |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |