Salt-proof bridges
Snowfighting professionals agree: salt is the most cost-effective material to preserve safe winter roads and reliable mobility in the face of winter storms.
It comes with a pricetag, however, beyond the cost of the salt. Corrosion from all sources creates an estimated $8.29 billion in damages every year to U.S. bridges. The problem is most severe along the Gulf coast and in snowbelt states where chloride deicers enhance the corrosivity of roadway runoff. TRB estimates that 14% of U.S. bridges are structurally deficient, mostly because of corrosion.
These conclusions led the Transportation Research Board to review best practices for bridge construction and maintenance. On September 24, TRB published NCHRP Synthesis 398: Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements.
The TRB report concludes that cathodic protection is "a viable corrosion control technology" and reiterates an FHWA policy statement that "cathodic protection is the only technology that can directly stop corrosion in reinforced concrete structures."
Pioneered 50 years ago in California and widely-used in Florida, Oregon and Missouri (and in Canada), cathodic protection provides "a significantly larger extension in service life compared with other corrosion mitigation systems," TRB concludes. But it is not being widely used because of its higher initial costs and unfamiliarity of highway agencies with its benefits, particularly because "corrosion is a moderate problem for the majority of the departments."
The report endorses use of cathodic protection on all bridges with marine exposure in coastal areas and for bridges on roadways on which five tons of deicing salt is applied each year per lane-mile.
Making the roadway environment compatible with use of the most cost-effective winter maintenance tool sounds like a good investment to us.
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