The crossing of the St. Croix River was difficult for the railway, since the original bridge across the river was very low and trains had to contend with steep grades on both sides of the river. This made it necessary to use helper engines and to make trains shorter.
The old bridge mentioned here is the Wisconsin Central Bridge Ruins. The Arcola High Bridge (aka Soo Line High Bridge) was build upstream.
Wisconsin Central Bridge Ruins, Somerset, WI (johnweeks.com)The Wisconsin Central bridge over the Saint Croix river was built in 1884 by the Union Bridge & Iron Works. The Wisconsin Central was pushing west, and this bridge was the last link to connect Milwaukee and Chicago to Saint Paul. The bridge features a number of very well crafted cut-stone piers. There were nine 160-foot deck truss spans, one 160-foot pin-connected though truss span, and 25 plate girder spans, each 30-feet long.
snippet of
Soo Line High Bridge (Wikipedia)The Soo Line High Bridge, also known as the Arcola High Bridge, is a steel deck arch bridge over the St. Croix River between Stillwater, Minnesota and Somerset, Wisconsin, United States. It was designed by structural engineer C.A.P. Turner and built by the American Bridge Company from 1910 to 1911. The bridge was listed on the National Register of Historic Places in 1977 for its national significance in the themes of engineering and transportation. It was nominated for its exceptional dimensions, beauty, innovative engineering techniques, and importance to transportation between Minnesota and Wisconsin.