As a professional engineer with 50 years of experience managing and designing large wastewater treatment plants, I found Tristram Metcalfe’s article on the Gare garage very insightful, and recommend strongly that Northampton follow his recommendations. It is well known among engineers that the biggest problem with concrete is the corrosion of the steel rebars. Water and salt cause the rebars to rust, which expands their diameter and spalls the concrete. Just like tree roots under the bike paths. The largest unreinforced concrete dome in the world, the Pantheon in Rome, Italy was built in 125 AD and is still in excellent condition because they had no rebar back then.
Of more concern is that the city failed to promptly react to the spalling reported by engineers in 2001, 25 years ago! A response then might have avoided the catastrophic condition now. This failure should be a wake-up call for the city to inspect all of its capital assets to ensure that they are properly maintained and that any design deficiencies are corrected.
Christian Bratina
Northampton