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Tuesday, December 16, 2014

Joe McKeever: The Kind of Bridge I Want


The Huey P. Long Bridge crosses the Mississippi River a few miles downriver from here. It was dedicated in 1935, a time when cars were small and narrow and governments needed to put men to work. That’s why they gave New Orleans its first bridge across the river and named it after this politician of dubious merit. (That’s a pet peeve of mine, but I’ll move right along.)

The problem with that bridge for all the decades since is that its two lanes were too narrow and curving for modern cars and trucks. Each lane was 9 feet wide, with no shoulders alongside. Signs forbade trucks from passing anyone, and motorists caught up on their prayers driving across it. It really could be frightening.

Then, in recent years, the government finally decided it was high time to upgrade that bridge, and shelled out something like a billion dollars to widen it and correct some of its flaws. These days, driving across that huge wide expanse is a pure joy. (The lanes are 11 feet wide, bordered by a 2 feet-wide shoulder to the inside and an 8-foot shoulder to the outside.)

What I wanted to tell you, though, was something an engineer said about the original bridge, something I find fascinating.

Now, in the middle of the bridge is a railroad track. Long freight trains cross it all the time. Motorists crossing the bridge will often feel a shudder from the heavy trains just to the left.

In the mid-30s, all locomotives were steam engines and were massive. Architects designing the bridge went with the assumption that engines of the future would just keep getting bigger and heavier, and thus the bridge would have to withstand the greater weight. So, they build a monster of a foundation with a massive structural framework. The Huey P. would be ready for whatever came.

What they could not have anticipated was the advent of diesel locomotives. So, instead of getting heavier and heavier, engines became lighter.

Engineers say the bridge was built to hold such a massive weight that the actual weight of the cars and trucks on it at any time is negligible.

Think of that. At any given time, a hundred automobiles may be crossing the river, many of them 18-wheelers. And yet, the combined weight and stress they produce on the bridge is negligible.

I love that.

It’s called redundancy and it’s a great concept.

“Redundancy” means something is constructed with backup strength and fail safe methods. If one part goes, the other compensates. Read more
I drove across the Huey P. Long Bridge on numerous occasions before the bridge was upgraded. Crossing the bridge could indeed be a frightening experience. In places the pavement had given away, creating holes in the road through which the Mississippi River could be seen far below. On at least one occasion an 18-wheeler went through the railings. Huey P. Long, nicknamed "the King Fish,"  was a controversial figure in Louisiana and U.S.  politics. Controversy also surrounds his untimely death--whether he was assassinated or accidentally killed by his own bodyguards. To read about Huey P. Long, click here.
Photo: nola.com

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