Work is underway to bore arrays of drainage holes through the concrete lining in two tunnels following the completion of short-mode TBM excavation at the tight, Po Shan Road site in Hong Kong. Excavation of the drainage tunnels was undertaken using a Robbins main beam TBM built for partial retrieval and relaunch, plus a bespoke short-run mucking out system. The short-mode system created for the job completed a total of 459m of tunnel to open an access tube from which the two drainage tunnels were driven.
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