This unique stone arch bridge sits at the east end of the Rockford Rail Bridge and is in great condition.
Originally constructed to cross a Chicago, Burlington & Quincy spur, the actual build date of the bridge is unknown.
Railroad documents give a estimated build date of 1896, which seems reasonable for the structure. The CB&Q built the mainline across the river near here in 1887. However, further research needs to be done. The bridge consists of a single helicoidal stone arch span, tied directly into the east abutment of the Rock River Bridge. It was constructed out of limestone.
Helicoidal arches are exceptionally rare for railroad use. These arches are known for the skewed spiral pattern, which is difficult to construct.
Fortunately, this arch remains in excellent condition, with very little defects. The area around it has since become a park.
The author has ranked this bridge as being moderately significant, due to the unique design. One other helicoidal arch is known in Illinois, located in Woodstock on a nearby line.
The photo above is an overview.