Primary Lining

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Primary Lining

Delivering stability and support


The primary lining phase delivers the stability of the tunnel structure providing immediate support to the excavated ground. This temporary supporting lining is commonly made of steel fiber reinforced shotcrete. When required, this phase also features the installation of reinforcement elements consisting of steel arched sections that have the shape of the tunnel contour.

Reducing costs and increasing productivity with the B.Zero TondoTM


Our patented B.Zero TondoTM Tunnel Support System is a new solution in tunnelling and provides extremely efficient first-stage support. B.Zero.TondoTM is unique tubular steel-arch ribs, filled with pumped concrete in-situ and offering greater structural efficiency than traditional steel-arch supports. Therefore fewer B.Zero TondoTM arches are needed, reducing costs and increasing tunnel productivity.