PROJECT PROFILE Summary The original tunnel had been carved out of Sydney sandstone in the 1930’s, and sandstone shavings were laid as a base in the tunnel above which a concrete track slab was laid, to which the rails had been attached. The tunnel was sloping downhill and the base of the tunnel was eroded, forming a drainage route over the half-century of use. The water running down had dissolved and washed away the fine sandstone aggrega

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