The Longbird Bridge in Bermuda, a swinging asymmetrical steel span, was built across Castle Harbor by the US Navy in 1953 to facilitate movements to St. David’s Island near the Kindley Naval Air Station (now the Bermuda L. F. Wade International Airport). Due to the high chloride environment, hot-dip galvanized steel reinforcement was used in the concrete approach and bridge deck.
In 2020, nearly 70 years after its construction, Bermuda’s MW&E began demolition of the Longbird Bridge to make way for a new, larger replacement structure. Samples of the rebar were collected for analysis by Zinc Connections, LLC, with the results described in an October 2020 case alert appearing in Roads & Bridges. Based on the analysis and published report, the galvanized coating on the rebar samples was in exceptionally good condition, except for one small bare area. The zinc coating thickness measurements on each bar ranged from 3.8 to 11.6 mils. When averaging all samples together, the zinc coating thickness was equal to 6.0 mils which exceeds the minimum coating thickness for new rebar in ASTM A767 Class 1 (150µm or 5.9 mils).