BNSF 4th Street Bridge (Middle)

Located in St. Paul, this concrete encased girder bridge carries a former Great Northern Railway mainline across 4th Street. At this location, several railroads converged on St. Paul and operated extensive terminal facilities. This bridge is the only structure carrying the GN, and is located immediately adjacent to the Northern Pacific Railway mainline bridge. The first bridge at this location consisted of a wooden bridge, set onto stone abutments and constructed in 1881. In 1902, the bridge was reconstructed with a new six track half through plate girder bridge, reusing the previous stone abutments. In 1927, the bridge was heavily altered, and the original girders were encased in concrete and new concrete floors constructed, giving the bridge its present configuration. In addition, the the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road) operated a timber stringer bridge across 4th Street parallel to the west face of the bridge, which was removed in the mid-20th Century. Currently, the bridge consists of a six track 47-foot half through plate girder span, set onto stone abutments and encased in concrete. The superstructure is unusual, with a concrete fascia, concrete encased floor system and decorative paneling on the fascia. The substructure also uses an unusual design, with a typical rectangular wall and no wing walls. The stone appears to consist of a grey sandstone, quarried at an unknown location. An unknown contractor fabricated the superstructure, and an additional unknown contractor constructed the abutments. In addition, a third unknown contractor completed the concrete encasement. Half-through plate girder spans were unusual for railroad use, as traditional through and deck plate girder spans were easier to build. These spans were constructed by placing the floor halfway up the girder, allowing for greater clearance underneath than a deck girder and greater lateral clearance than a through girder. Since the initial construction, the bridge has seen no significant alterations, and remains in regular use. Today, only the eastern and a middle track are in service, while the others have been removed and the space used as access roads. Overall, the bridge appears to be in fair condition, with no significant deterioration noted. The author has ranked this bridge as being locally significant, due to the unique design.