If you want to know why the south sound wall on Interstate 94 through southeast Minneapolis now sports a crazy-quilt pattern of camouflage-colored metal panels, the short answer is: a gusset plate.
The long explanation behind the underwhelming arrangement of earth-toned rectangles not only makes for a more satisfying read, it starts to shed light on another perennial question of near philosophical importance: Why does the Minnesota Department of Transportation spend so much money to make our eyes hurt?
First, the back story.
When the Interstate 35 bridge collapsed in 2007 (due to a now notoriously undersized gusset plate) it cut off a primary route into downtown Minneapolis. Until the replacement bridge could be built and put into service 13 months later, the existing freeway system around downtown groaned under the crush of diverted traffic. In response, MnDOT re-striped I-94 between Hwy. 280 and downtown, adding a lane in each direction.
The reduction in congestion was so great that the public pushed MnDOT to make the new eight-lane configuration permanent. Additional traffic increased freeway noise in the East River Road area to the south. In 2009, MnDOT began planning a new sound wall, and by the end of 2010, a 20-foot-high concrete-pier-and-wood wall had been constructed.
Immediately, noise levels dropped off south of the freeway. Soon, Prospect Park residents to the north noticed that the very same noise was being reflected off the new wall, bouncing freeway racket into their previously tranquil lives.
Oops.
The well-educated and well-organized enclave near the University of Minnesota rallied, putting MnDOT engineers back to work. Sound testing was performed. Reports were generated. Sound-absorbing materials were studied. "Action plans" were formulated.