Lining or relining of tunnels

A method of lining or relining a tunnel, for example a sewer, comprising the steps of overlapping the edges of a pipe including a single longitudinal split in order to reduce the cross-sectional periphery of the pipe, the pipe being of a material of sufficient pliability to permit the overlapping of its edges without fracture, inserting the pipe with overlapped edges into the tunnel, re-aligning the edges of the pipe and thereby expanding the pipe in the tunnel, securing the edges of the pipe together to retain the pipe in its expanded form, deforming a collar into a shape in which a first dimension of the collar is increased and a second dimension is decreased, inserting the deformed collar into the tunnel with its said first dimension generally along the tunnel, expanding the collar back to its original shape, rotating the collar about an axis generally transverse of the tunnel to locate the collar in the tunnel and engaging the pipe with the collar when expanding the pipe in the tunnel.