When we think of bridges, it is the dramatic and monumental long spans that come to mind first, especially the lithe suspension bridges such as the Golden Gate and the pure geometric arches such as Sydney Harbour. But the majority of bridges are not such spectacular structures. Most of them are ordinary overpasses, with spans of 30 or 40 feet, carrying roadways or rails across other thoroughfares or over small streams. You see such bridges by the dozen on any drive down the Interstate. They may be lacking in glamour, but they are more representative of a bridge builder's art.
The engineering and construction of girder bridges are pretty routine these days, but the bridges are not quite standard items you order from a catalogue. The girders, whether of steel or concrete, are custom-build for each bridge, then trucked to the site and hoisted into place with a crane. The designer still has scope for variation and creativity, and it shows out on the highways: some overpasses are prettier than others.
How does a writer manage to turn out such tortuous syntax? It happens when he shovels phrase after phrase onto the page in the order which each one occurs to him.
The problem is that the order in which thoughts occur to the writer is different from the order in which they are easily discovered by a reader. It’s a syntactic version of the curse of knowledge. The writer can see the links among the concepts in his internal web of knowledge, and has forgotten that a reader needs to build an orderly tree to decipher them from his string of words.