Bridges are functional, can be quite lovely, and sometimes have historic value. The bridges along the Midtown Greenway between Humboldt and 20th Avenue South are a perfect example: they are pretty, keep the street grid mostly cohesive and some are historic. In the coming years we are going to have to decide if their historic value is enough to justify keeping them, or if they should be replaced.
The corridor was originally a rail line that was built along the southern border of Minneapolis. As the city grew, the at-grade corridor became problematic. The area was mixed use–industrial and residential–but industry arrived first, with residential needs moving in later. The City of Minneapolis and the Chicago Milwaukee and St. Paul railroad agreed to a grade separation. But unlike other grade separation projects of the time, which elevated the track, from 1912 to 1916 a 3-mile trench was excavated, dropping the track below grade. This allowed the City to continue its expansion south and resulted in thirty-seven bridges crossing over the track depression that we now use as a bicycle and pedestrian trail.
In 2005 this corridor was designated the Chicago Milwaukee and St. Paul Grade Separation Historic District and is now on the National Register of Historic Places. The corridor was considered historically valuable because of its role as a solution to a community and city planning problem and because of the construction and design of the grade separation, including the bridges.
The bridges are important to the historic designation because there are no longer any historic buildings on the corridor. Buildings which contributed to the corridor’s original use are gone (there are some adjacent buildings of historical value, but they aren’t considered contributing resources) and the rail has been removed from the corridor, taking with it the infrastructure remnants of its original use. The lynchpin in the historical designation, the remaining physical structures which retain design elements of the original use and contribute to the corridor’s historical significance, are the bridges.
Within the Historic District there are thirty-seven bridges, twenty-six of which are considered historic resources. Most of the bridges are approximately 100 years old. In 2007 the City released a study about the health of the bridges along the corridor and it included recommendations for the future. The study recommends considering some of the bridges be converted to bicycle and pedestrian-only traffic at the end of their useful lives and that others be completely replaced in order to retain the street grid and their function as important north-south traffic corridors. Some of the bridges have already been replaced: the Chicago Avenue bridge was replaced in 2005 and Park Avenue in 2006. We should expect to see more of the remaining bridges come into question in the next couple years, as the end of their useful lives draws nearer and conversations about the potential for transit on the corridor ramp up.
If you haven’t taken a close look at the bridges, I recommend it. There are seven types of bridges along the corridor. They are pretty neat (in my opinion) and it is really easy to ride or walk past, without realizing how interesting they are.
At first glance, they might not strike you as very beautiful, but specific attention was paid to their aesthetics when they were built, as they were highly visible in a new residential area. You can see some of the design detail along the pedestrian portions and parapets.
Smoke guards and ledges to accommodate water and sewer lines were also included in the design. The undersides of the bridges just west of the Midtown Exchange offer a great view of these elements.
My favorite design detail is found on the piers, where you can see the wood grain, from the piers’ casting. They were cast in place, instead of moving precast piers into the trench.
Depending on how you feel about the value of historical design, new transit proposals and the residential development along the corridor these bridges can be important historical documents or barriers to progress. Either way, they’re worth checking out, especially since we don’t know what the future holds for them.