Tunnelling Products Range


Hex Head Straight Bolting System and Plastic Socket

Bolts and the accompanying ‘cast-in’ sockets are used as connectors to fix tunnel segments together and can be used in both radial and circumferential sides of the segment.  Bolt is screwed into the socket in order to ensure the correct geometry of the ring but also to compress correctly the gasket.

Additional accessories like washers and grommets can be installed in order to ensure the accuracy of the connection.  We manufacture the complete range of bolts in various lengths, diameters and material properties.

Curved Tunnel Bolts

Curved bolts are used to permanently fix tunnel segments together through a radius hole.  They can be applied to both radial and circumferential joints.

Additional accessories like washers and nuts are also offered by Cooper & Turner. We adapt the lengths, the diameters and the materials to the needs of our customers.

Guide Rods

Guide rods are extruded cylindrical plastic part that come in a variety of diameters and lengths to suit different ring sizes. They can be glued into cast semi-circular grooves in the radial side of the concrete segment.

Cooper & Turner also developed a new “anchored guide rod”, that can be directly installed in the concrete segment mould. Once erected, the rod will facilitate the ring erection and increase the stability of the assembly.


Packers for segmental linings are usually installed on the circumferential joints in order to transfer TBM’s hydraulic loads between adjacent rings.

They can be manufactured in different raw materials and can be made self-adhesive or delivered with glue.

The size and the shape of the packers are adjusted on demand.


MODULOCK is the circumferential connector developed by Cooper & Turner.  Thanks to our unique clip-on fins, we ensure an easy and firm connection between segments, and perfect compression of the gasket.

The shape of our product and its shear capacity facilitate the centering of the segments on the circumferential joints.  Thanks to its experience, Cooper & Turner has developed a full range of MODULOCK in order to be in line with the different needs of our customers.

Our product is, for sure, the most modular connector on the market.


Alignment dowels are used in conjunction with a straight bolt connection system to assist alignment during the erection phase on the circumferential joint.  They are placed into corresponding cast voids in the segments to guide the installation of the next segment.

They can be manufactured with or without steel bar reinforcement, depending on the shear resistance required.


Threaded Grout Lifting Sockets

Grout sockets are specially designed to allow primary or secondary grouting work after installation of the segment.  All our sockets can be also used as lifting sockets for the handling and installation of the concrete segments, thanks to a dedicated lifting pin installed on the TBM’s erector.  A variety of designs can be supplied to suit any requirements.

Dedicated non-return valves and sealing plugs, with EPDM or hydrophilic O-ring, can be supplied.  Cooper & Turner can also manufacture a large range of steel grout sockets when it is required.


Intrados Sockets

We also proposes a large range of intrados sockets designed in order to allow the installation of additional brackets/services inside the tunnel after installation of the ring.  The sockets can be made in steel, in plastic or in ceramic (fire resistance).

We developed a full range of holders in order to install these sockets inside the segment moulds.

Barcode Plate

Our Barcode Plates are used for the traceability of segments. It allows to have an access to the reference of the segment, of ring, data of production, storage and many others…

The Barcode Plates are easy to install in the mould thanks to our unique design.  After demoulding of the segment, the plate is visible on the intrados of the segment.



For each Cooper & Turner’s product there is a holder for its installation in the segment mould.

Our design team always think about the way to install our accessories inside the mould.

Whatever the position of the insert, we developed the solution.



All of our products have been designed and developed by experienced engineers specializing in the tunneling market.  Our designers work on the constant improvement of our products, as well as on the design and the production of new testing processes and tools.  Our computer simulations are always confirmed by empiric tests made in laboratory.