We bridge difficulties. We like a bridge over troubled waters. We needed a bridge into the new millennium. Bridges have a hold on us in a way that other examples of civil engineering do not. And we often don't notice them as we use them. Although I had traveled on the Natchez Trace Parkway many times, upheld by a bridge in Franklin, Tennessee, I had never looked down and appreciated the span until alerted to it a couple of years ago. It is a beautiful, big, parabolic concrete arch which I now get off and admire fairly often. According to _Bridges: The Spans of North America_ (Norton) by David Plowden, I am not alone. This bridge "is unlike any heretofore built in America and has been the recipient of innumerable awards." Calling attention to the bridges we take for granted, and telling a history of American bridge building, Plowden's book is fittingly big, and displays his beautiful black and white pictures in large format, splendidly reproduced. It is properly sized for the coffee table, but the text is appropriately comprehensive, and as worth reading as the pictures are worth admiring.
_Bridges_ is divided into chronological sections based on the materials used: stone and brick; wood; iron; steel (divided into three time periods, since there are so many steel bridges); and concrete. Erecting a stone bridge was expensive and time consuming, especially compared to using wood. There are more miles of wooden bridges than any other type in America, although Plowden has little good to say about the "cult of the covered bridge" which has obscured the trusswork he thinks is the important part of these wooden bridges. Iron was used for bridges for only a short time, and iron bridges are the rarest of bridge artifacts. Concrete bridges are the way to go for the main bridge-building impetus in America, the highway system. Reinforced concrete does extremely well for piers to hold bridges up, as well as for the flats that carry traffic. Plowden spends many pages on the most famous type of bridge, the steel spans, and his pictures of the Golden Gate Bridge and the Brooklyn Bridge present them in new ways, and he hurtles through the engrossing stories of their construction because they are relatively familiar. The stories of lesser known bridges, such as the wonderful Eads bridge in St. Louis (built by Captain James Eads, of few engineering credentials and no bridge experience) bring to light many surprising difficulties and solutions the bridge builders came up with.
Plowden's history serves as a demonstration of engineering problem-solving. Each bridge is unique in purpose, location, and difficulties of completion. This is true even in replacement bridges. Many of these beautiful photographs show bridges that are no longer existent. There have been bridge failures, of course, but usually bridges built in the nineteenth century show signs of distress, and are called out of commission. Sometimes railroads simply no longer need a particular link. There are, however, new vistas for bridge building, especially in the straits and bays that have needed bridges and now have proposals for bridges meeting new engineering and economic abilities previously unavailable. Plowden is confident that utility will continue to be combined with beauty, and his handsome book supports such confidence.