GMA Garnet and Birkenhead - Australia’s first double-leaf drawbridge
The Birkenhead bridge in Adelaide, South Australia is the first operational double-leaf bascule drawbridge in the country.
Built in 1940, the 78-year old bridge links Port Adelaide to the Lefevre Peninsula with over 16,000 vehicles travelling on the bridge each day.
Over the years, the bridge has undergone modifications and scheduled mechanical and electrical maintenance. However, the biggest threats to the bridge are elements of nature such as salt, moisture and wind.
In March 2016, 40 hand rails with heritage listed capping beams over three metres long and 42 pillars on each side of the bridge require restoration. Six new pillars were added for the reconstruction of the footpath.
According to the contractor - AFL Services General Manager Adam Levi, the excess rust (Class D) was first removed with a needle gun,
followed by abrasive blast cleaning using GMA PremiumBlast™ garnet to remove the lead coating to achieve a profile of 40-60 µm.
The surface was then coated with a zinc primer based on AS2312 PUR5 standards.
“For the first time, we performed the blast cleaning works in an inflatable work station to ensure the air and water quality at the work site were not affected. Cleaning up was also easier as the contained space created negative pressure for easy extraction of dust and blasted materials,” Adam said.