Totally agree with sentiment here. Call the bridge Memorial Bridge and put a plaque on either end. The incident shouldn't be forgotten nor should it shape the look and functionality of the new bridge. Otherwise, we'd have to engrave faces all along every highway in America. Maybe put a small statue nearby or near a walking path. That's it though.
FITTING MEMORIAL: ACCOUNTABILITY
The bridge should be commemorated by holding those responsible for not fixing it accountable.
MEMORIAL IN THE DETAILS
Sounds like MnDOT wants to put up another boring bridge, which is fine. However can the detail be finished in a way so it is not like every other interstate bridge. For example a bridge with decorative metal work ... Maybe instead of calling a memorial bridge. Since the birthplace of Minneapolis is just up the river with the falls of St Anthony, call it the St. Anthony Reflection Bridge. The decorative metal work could play of the idea of reflection of the river of victims and their families.
HOW ABOUT A PARK?
I think they should have a beautiful area set aside, display a large piece of cement, and bent rebar, in memory of those that have died, and have a beautiful plaque displaying their names. This area should be kept beautiful in all seasons and lighted. Showing that they will never be forgotten!
SCULPTURE FROM DEBRIS
Make a sculpture out of the leftover debris and put it in a location near the collapse sight. Have the base of it be made of some sort of granite w/the names of the lost ones involved in this tragedy.
A GRAND NEW BRIDGE
The bridge itself should be a memorial. Rather than plunking down some object, make a safe, beautiful, cutting-edge structure to honor the dead. Calatrava, anyone?