SYDNEY HARBOUR BRIDGE.

Otago Witness, Issue 3972, 29 April 1930, Page 23

SYDNEY HARBOUR BRIDGE.

GREAT PAINTING JOS

WHEN THE ARCH JOINS

(From Our Own Correspondent.)

SYDNEY, April 10. Not the least of the colossal tasks associated with Sydney Harbour bridge is the painting of it. At the outset it is having three coats —first what is known as the shop coat of red lead, next a coat. of battleship grew, a colour selected for its hard wearing qualities, and then a coat of slightly lighter grey. The giant approach spans have already had their first two coats, and the arch, a-s far as it has gone over the harbour, is now getting its first field coat of battleship grey. The painting of the massive steel structures, to prevent the risk of corrosion by rust, will practically be a continuous process for all time. It will take about 12 months to paint the whole bridge, from terminal abutment to terminal abutment, when it is open for traffic.

About 100 painters are busy with brushes on the bridge to-day. By the time they have reached one end of the bridge it will be awaiting another coat at the other end. It will be practically an endless process to guard against corrosion by rust, the effects of which on exposed steel are said to be costing the world about £500,000,000 a year. The cost of painting Sydney Harbour bridge can be appreciated by comparing it with the famous Forth Bridge which takes 50 tons of paint for one coat alone, and occupies about 30 men continuously in that task. The Colossus bestriding the harbour would have cut a wonderful figure, especially at night, painted in white, but it would have, quickly lost its look of virginal purity. Battleship grey has been chosen, like the Vicar of Wakefield’s homely wife, not for its prettiness, but for its hard wearing qualities.

Visitors to Sydney between September and November are likely to be afforded the spectacle—unique as an engineering feat at least in Australia—of the two halves of the massive arch suspended over the harbour meeting and locking together at the centre. From that point the crane will gradually creep back to either shore of the harbour, dropping supports as it goes for the construction of the deck, or roadway, for rail, motor, and other vehicles as well as pedestrian traffic. The fact that the error in directional alignment of the steel work in the giant arch is less than an eighth of an inch is a nice tribute to the builders, Dorman, Long, and Co., and to the man, especially when one remembers that tlie steel work erected to date across the water weighs about 18,000 tons. The full weight of the steel work in the arch when completed will be about 37,000 tons, or 50,000 tons i taking the whole of the bridge, including the approach spans. If visitors to Sydney want to get a fair idea of the enormous proportions of the bridge, they cannot do better than take a tram to Miller’s Point, hop off at -the approach span, and get a close-up of it from that angle; or, tfl take another angle of it, get the ferry to M’Mahon’s Point, and pass under the arch of it. Big structures are an expression of a city’s pride and stability. Sydney will be justifiably proud of this job. The seventh panel of the bridge on the northern side of the harbour is likely to be completed in about a fortenight. Each of what are known as the bottom chord members in the sixth panel weigh about 110 tons.