Seventh Street Improvement Arches [SEP] material used
Seventh Street Improvement Arches
The Seventh Street Improvement Arches are a double-arched masonry highway bridge that formerly spanned the St. Paul and Duluth Railroad tracks in Saint Paul, Minnesota, United States. The Seventh Street Improvement Arches are historically significant for its rarity and the technically demanding nature of its skewed, helicoidal spiral, stone-arch design. The bridge is one of the few of its type in the United States, and is the only known bridge of its type in Minnesota. It was built from 1883 to 1884 by
sewer for the crossing of Phalen Creek. These improvements were necessary because the hill on Seventh Street needed to be rebuilt to lessen its steepness, so streetcars could travel between downtown and the Dayton's Bluff neighborhood. The Seventh Street Improvement Arches bridge posed a special engineering challenge because the street crossed the St. Paul and Duluth tracks at a 63-degree angle. The bridge also had to carry sewer and water pipes and match the rest of the profile of the regraded hill, making a substantial amount of fill necessary. This precluded the construction