Decades of deferred maintenance caused the Williamsburg Bridge to deteriorate significantly. This was worsened by a design flaw during construction: instead of galvanizing the main cables to prevent their corrosion, workers placed a mixture of "slushing oil" as a cost-saving measure. By 1912, some of the smaller cables in the bridge's anchorages had already snapped. In 1922, a galvanized sheath was placed around each of the main cables. However, damage still occurred, and in 1934, water in the main cables caused the wires to rust. In 1944 and again in 1963, workers poured oil treatments onto the cables in attempts to prevent the corrosion. Workers later added several support towers on either side of the main span to supplement the suspension towers. In 1969, inspectors found varying degrees of corrosion under the bridge's outer roadways. A 1978 study of the Williamsburg Bridge, as well as of five other bridges in New York City, found that there were varying degrees of corrosion on the main cables' individual strands. Cracks were also found in the bridge structure itself. Out of the six bridges examined in 1978, the Williamsburg Bridge was the only crossing that was found to have corroded suspension cables.