History
The Johnson Street Bridge was designed under the direction of Mr. F. M. Preston, City Engineer in 1920. This is a Bascule-type bridge in which one end rises while a counter weight lowers on the opposite end. When it was built, the Johnson Street Bridge had two separate Bascules, the Railway section and the Highway section. However the Railway section has since been removed due to lack of use.
The Strauss Bascule Company Limited, which held the patents on the design, prepared the design for the bascule spans and the operating machinery. Joseph Strauss later went on to design the Golden Gate Bridge in San Francisco. The superstructure of the bridge was fabricated in Walkerville, Ontario and contains 100 tons of steel. The City of Victoria Engineering Department built the sub-structure of the bridge. It required 10,000 cubic yards (7,600 cubic metres) of concrete. The main opening span is
148 feet (45 m) in length and when in the open position is balanced over a 45-foot (14 m) fixed span. The eastern approach is spanned by a 110-foot (34 m) fixed girder while the western approach has a 73-foot (22 m) fixed girder.
The counter weight block on the highway span is a hollow concrete structure and contains a number of smaller concrete weights and tips the scale at over 780-tons. It balances the 350-ton opening span. The linkage is moved by two large racks which are driven by two 75 horsepower (56 kilowatts) electric motors.
The Johnson Street Bridge was completed at a cost of $918,000 and opened in January 1924. The original deck of the bridge was constructed of wood timbers. Besides being slippery in wet weather, the timber absorbed water and became heavier which affected the balance and placed excessive loads on the opening machinery. The timbers were replaced by an open steel grid decking of constant weight in 1966.
In 1979, extensive repairs were made to the superstructure, which had become severely corroded. The blue paint now on the bridge was selected because the oxides of its pigment are the same colour as the paint so that little fading of the colour occurs.
In 1995, abnormally high temperatures caused the steel decking to expand to the point the bridge would not open or close properly. This necessitated the removal of about 1-inch (25 mm) of the decking.
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