On Nov. 11, The Times Record published a guest column written by Doug Bennett on the fate of the Frank J. Wood bridge between Brunswick.

The thrust of Mr. Bennett’s column was that the decision whether to renovate the current steel truss bridge or replace it with a concrete and steel highway bridge is basically an economic question. Mr. Bennett cited figures to “ prove” that the difference between renovation and replacement is on the order of $10 million over the lifespan of each alternative.

The accuracy of the figures cited is highly questionable. The difference he cites is based on an assumption that renovation of the existing span will require $6.2 million for maintenance during its lifespan, an average of about $82,000 per year. He contrasts this with the life cycle cost of a new bridge, and concludes that a new concrete and steel bridge would be nearly maintenance-free over its 100 year life, and would cost only an average of $7,000 per year to maintain. If anyone imagines that concrete structures can have a 100- year life with little maintenance, a brief visit to Bath to observe the condition of the overhead viaduct that is being demolished would indicate the reality about concrete structures. In fact, the technical literature on the life span of concrete bridges indicates a hot debate on their useful life, with some engineers contending that for the ordinary concrete bridge built today, a lifespan of 50 to 60 years is more appropriate.

Even more inaccurate is the method of the calculation Mr. Bennett uses. Adding future maintenance costs to today’s cost of construction is like adding apples and oranges. The calculations which financial analysts actually use to compare life cycle costs is to bring all costs back to their present value, to today’s value. That method takes account of the fact that a dollar to be spent 75 years from now is worth far less than a dollar today. When the $ 6.2 million in maintenance Mr. Bennett projects over 75 years are reduced to their present value, they amount to about $2.5 million in today’s terms. If that is added to the cost of renovation of the current bridge that Mr. Bennett uses, the total in present day terms is about $ 19.5 million, about $4 million less than what he gets by adding apples and oranges.

But the question of cost and lifespan is really secondary to what is far more important. The decision of whether to renovate a historic structure is really a question of values. For example, no doubt that one can often replace an historic structure with an ordinary new building at a cheaper cost. For example, the historic Bowdoin Mill and Fort Andross could have been demolished and replaced by modern office buildings, more efficient and perhaps less costly. But what a tragedy that would have been.

The replacement of the Frank Wood Bridge would likewise be a tragedy, as well as economically shortsighted. Financially, the difference cited by Mr. Bennett is minuscule compared to income that tourism brings to our area. Eighteen million tourists in Maine spend over $5 billion every year, the largest industry in the state. And how do we in this area fare in the competition for those tourist dollars? Pretty well, it would seem. And why? Because we have made a conscious effort in this community to preserve its historic nature. The Frank J. Wood Bridge, and the mills at either end, are a major part of our historic environment. Literally tens of thousands of tourists come to our area because we have honored our historic past, bringing in tens of millions of dollars every year. Some communities in this country have even made their historic bridges into magnets for tourism, with art festivals, music festivals, community festivals centered on their historic bridges.

I understand that both Topsham and Brunswick and their business sectors want to preserve and improve the business climate. But it is a delusion to imagine that destroying an historic bridge, one of the last ones of its type in Maine, and replacing it with a concrete and steel highway bridge will make the community more attractive and more prosperous. Surely we can be more creative than that.

John Graham is president of the Friends of Frank J Wood Bridge and a member of the Topsham Historical Commission.