Editorial: Bridge hopes in details
A lot has changed about bridge building since the days when the Stillwater (Minn.) lift bridge went up or even the Eisenhower bridge carrying Hwy. 63 into Red Wing was constructed.
Lawrence Thomas of Diamond Bluff worked on the latter. The retired Pierce County Highway Department employee also was on a contractor's crew in the 1960s for the I-35W bridge that collapsed last year in downtown Minneapolis. While Thomas expressed interest this summer in the "nuts and bolts" of such projects, he never mentioned another aspect of modern bridge planning: appearance.
The Minneapolis Star Tribune reported this spring a citizens group had input into the design of the new 35W replacement. The group not only voted on the make-up of the bridge's retaining walls, but on the color of the span itself. They were given the opportunity by Figg Bridge Engineers, part of a construction team led by Flatiron Constructors, winners of the $234 million contract for the job.
An all-day meeting involving over 80 people preferred white over sandstone for color, which made the chairman of the Minneapolis Heritage Preservation Commission happy. He'd feared the bridge would end up being beige, contending white would fit in better with the nearby Third Avenue and 10th Avenue bridges, plus the riverfront grain elevators. The final hue tilted toward gray, however.
The texture for retaining walls and abutments was chosen, too. Two of the designs called for concrete, with one containing engraved quotes about the Mississippi River. The one ultimately favored consisted of mesh baskets filled with stones. Some of those wanting the baskets (known as "gabions") figured they'd be harder for vandals to cover with spray-painted graffiti.
As far as pier design, participants at the meeting (referred to as a "charrette") tended to focus on how much parkland the piers would take up. Although a few regarded the larger design as "an elephant's foot," that one, featuring curves continuing the arch formed by the main span, won. Its sturdy look may have helped it gain victory.
On the other hand, sturdier solid concrete railings didn't get quite the backing given open metal ones or partially open ones. That group verdict occurred despite the metal railings having higher maintenance costs. It also happened even though there's not much time for drivers to view surrounding scenery at freeway speeds. The director of the Mill City Museum countered with a reality of modern commuting: "We're not always going to be going over this bridge at 55 mph," he said in a nod to today's traffic jams.
Monuments and lighting were other issues which were resolved. Hopefully, this "sweating out" the details will bode well when it comes to assuring the I-35W bridge stands up for a long time.