The Longfellow Bridge here in Cambridge, built in 1906, is going to be partially shut down for the next three years. The project is forecast to cost about $260 million, though previous construction cost forecasts in Massachusetts have been optimistic (e.g., the Big Dig was originally planned at $2.8 billion but ended up costing close to $15 billion). The project has already generated some controversy due to the fact that Governor Deval Patrick imposed a rule that excluded non-union workers from contributing (Boston Globe editorial).

I was interested to know how the cost of renovating the bridge compared to the cost of its construction but none of the news articles on the subject of the bridge project mentioned the original cost. Nor does Wikipedia. I found a “Cambridge Bridge Commission Report” on archive.org that on pages 53 and 54 summarizes the cost. The “total paid for new bridge” was about $2.5 million. In today’s dollars that’s approximately $65 million. In other words, assuming that this project comes in within its budget, renovating the bridge will cost roughly 4X what it cost to build.

If you’d like to play with the figures, I hired Cristian Blendea of Bucharest, Romania (via Guru.com) to prepare an Excel spreadsheet with all of the numbers from the book: Longfellow-Bridge-Construction-Cost

[When the project is all done, the current four lanes for cars (two in each direction) will be reduced to three (just one lane from Boston to Cambridge), so if examined in terms of cost per lane of travel, it was $16.25 million to construct and will be $86.67 million to renovate, a 5X increase in cost.]