Twin Spans in Minnesota: The Answer

Photo courtesy of Minnesota Dept. of Transportation

And now to the answer to the question of Twin Spans in Minnesota, which is in connection with the recently published article on the Winona Bridge (see here). Some people may contest to the fact that there are three such twin spans- consisting of the original span and a sister span built alongside it to alleviate traffic. It is true that there is another pair of bridges located 60+ miles down south along the Mississippi River in LaCrosse, Wisconsin with a cantilever truss bridge (built in 1939) and a tied arch bridge (built in 2001), the latter of which carries eastbound traffic featuring US Hwys. 14 and 61 and Wisconsin Hwy. 16.  However, the crossing is only a mile southeast of the Minnesota-Wisconsin border, ironically crossed by another pair of bridges built in the 1970s. Technically, when speaking of borders, the LaCrosse Bridges do not count.

The first crossing that featured an original bridge which later had a sibling span to serve traffic is the Hudson Bridge, spanning the St. Croix River at the Minnesota-Wisconsin Border, west of Hudson.  Originally carrying US Hwy. 12, which was later superseded by I-94, the Hudson Bridge’s history dates as far back as 1911, when the first crossing was built and christened The Hudson Toll Bridge. A product of the Central States Bridge Company of Indianapolis, the 1051-foot long bridge was built on a causeway which started from the business district and ended with the driver making a 10° incline up the Warren deck truss approach spans, before crossing the 136-foot long polygonal Warren through truss span with Lattice portal bracings and riveted connections.  After that and crossing the approach span the driver ended up in Minnesota. Tolls were collected on the causeway on the Hudson side.

Photo courtesy of MnDOT

Yet because of the increase in boat and auto traffic and the coming of the freeways that would later shape the Twin Cities Metropolitan Area, it necessitated the construction of a new bridge, located a half mile south of the Toll Bridge. When completed in 1951, the truss span was relocated to LeFarge, Wisconsin, where it spanned the Kickapoo River before its removal for safety concerns in 1986. The causeway itself was retained and now serves as an observation point with many piers from the old bridge to be seen on both sides of the river.

The Hudson Interstate Bridge was completed in 1951 and featured two lanes of traffic encased in seven spans of Warren through truss bridges with riveted connections and X-frame portal and strut bracings. The main spans, featuring a cantilever through truss span totalled over 700 feet with the entire structure totalling 1,700 feet. The Interstate Bridge served as a single entity until 1973, when a girder span was built to the south of the bridge and accomodated eastbound traffic of US Hwy. 12. The truss span served westbound traffic. Both spans were reconstructed in the 1980s when US 12 was converted to I-94.

Person crossing the Interstate Bridge. Photo taken by MnDOT

Unfortunately when flooding occurred in 1993, both states made haste to build a new span to replace the truss structure for floodwaters damaged the structure to a point where it not only could no longer carry heavy traffic, but it was literally falling apart, with cracks appearing in the steel. In fact the situation was so dire that an emergency lane on the newer structure was made for heavier vehicles going westbound was created. Officials claimed that had this not been done, the bridge would literally have fallen into the waters of the St. Croix, taking many lives with. When the new span opened in 1995, little effort was need to push the 1951 truss spans into the water and cut them up unto scrap metal. The truss spans did not last even a half century because of the wear and tear that had occurred on the structure. Yet had the flooding not occurred in 1993, chances are likely that the bridge would still have been retained even though plans would have been in the making for a new bridge anyway because of the high volume of traffic combined with the events that happened on the I-35W Bridge in 2007. How long the bridge would actually have survived remains unclear.

Since 1995 there has not been a double-span arrangement similar to the Hudson Bridge in Minnesota, but with plans in the making for a sibling span in Winona, we will have the second such arrangement ever built in the state, but the first one in 21 years when completed in 2016. Given the height of the 1940 cantilever truss span combined with the scheduled rehabilitation to follow, it is highly doubtful that the Winona Bridge will suffer the same fate as the bridge in Hudson, but that depends on how the structure handles traffic both on the highway as well as those in the water when passing underneath. If people treat the bridge with care, the bridge will perhaps last a generation or two longer than expected.

Some information and write-ups can be found by clicking on the links marked in the text, including those by John Weeks III.  Special thanks to Minnesota DOT for the information and photos provided for this article.

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