As best as I can determine, only about three grumpy old men — John Walker, John Brummett and yours truly — have raised questions about replacing the aging Broadway Bridge with a super-duper new bridge at a time when money is tight. The Highway Department has $45 million committed to spend. My guess it will cost a lot more.
We've tried to investigate the question of whether repair would be cheaper and satisfactory. Highway officials insisted replacement is the only smart way to go.
Last night, I received a temperate letter from an engineer who offered his own opinion. He doesn't want to get into the issue publicly, but he agreed to my request to republish his note without attribution. He makes the case for replacement and suggests emulating the Minnesota bridge shown above:
I have been a civil engineer for 41 years with world wide experience. I assure you that the Broadway Bridge is not economically repairable. The best way to repair it would be to demolish it and build another one that looks just like it. If you want to see for yourself get on Riverfront Drive headed east from the Care Link Building. (You won’t even have to get out of your car.) When you get under the Broadway Bridge there’s a driveway to the south that you can pull into. Roll down your window and look up. You can see several areas where the reinforcing bars in the concrete have rusted, expanded, and broken the concrete. There are numerous patches. All the patches do is cover up the rusted rebar. The bars on the bottom are in tension. The main function of the concrete on the bottom of a beam is to protect the rebar from the elements. The concrete on the top side of a beam carries a load and are in compression. Once water and salt get inside the concrete the bridge is lost. There are some tests that can be done that involve sending sonic waves through the concrete but they are expensive and not definitive.
The Little Rock Engineers Club had a program a few weeks ago about the replacement of the Lowry Street Bridge (Cty Rd 153) over the Mississippi River in Minneapolis-St.Paul. They replaced an old steel truss bridge with a combination steel truss and concrete bridge. The result is a new bridge that’s far more beautiful than the old bridge. (the people in the neighborhood were very fond of their old truss bridge and wanted a new one that looked like it. They got something much better.) The best thing to do is have AHTD hire a bridge architect and design a beautiful bridge. It won’t cost much more than an ugly interstate bridge.