Metro Tunnel
Formwork

Metro tunnel formwork is a purpose-built formwork system used to form tunnel cross-sections accurately and repeatably in metro lines, station structures, cut-and-cover tunnels, underground passages and reinforced-concrete transport infrastructure. Rayf Teknik brings its site experience in slipform and special engineered formwork to metro tunnel projects, developing project-specific formwork solutions based on the tunnel's span, height, cross-sectional geometry, concrete thickness and available working space.

Not every metro or tunnel structure shares the same geometry. Reinforced-concrete tunnels may have rectangular, arched, oval or project-specific composite cross-sections. Metro tunnel formwork therefore needs to be designed around the project's reinforced-concrete details rather than built to standard dimensions. Formwork faces, the load-bearing chassis, working platforms, internal and external supports and the travel system are assessed together so that the system runs smoothly on site.

Travelling and Reusable Tunnel Formwork System

On long metro lines, identical or similar tunnel cross-sections may be repeated many times. On such projects, transferring the formwork to the next pour section on a travelling carrier system, rather than completely dismantling and re-erecting it after every pour, offers a major advantage. Once the concrete has gained the required strength, the formwork faces are released from the concrete and the system can be moved to the new working area on rails, wheels or a project-specific travel mechanism.

The approach to formwork movement, concreting programme and site organisation that Rayf Teknik applies in slipform provides an important engineering foundation for the development of metro tunnel formwork. Concrete supply, reinforcement works, formwork set-up, concreting and preparation for the next stage are all planned within a single work cycle.

Designing metro tunnel formwork involves far more than the tunnel's internal dimensions. Reinforcement density, fresh concrete pressure, working space, mechanical penetrations, niches, connection points and other reinforced-concrete details are all built into the system design. It is essential that the formwork faces hold their geometry under concrete pressure and can be reused with the same precision after every pour.

Where project conditions allow, systems manufactured by Rayf Teknik can be redeployed in later stages or on other projects. The existing load-bearing structure can be retained while panels, connections or support elements are revised to suit a new tunnel cross-section. In this way, the formwork investment made for the first project continues to deliver value on subsequent projects.

As with slipform systems, site supervision can be provided where required to companies that purchase metro tunnel formwork. Technical support during installation, the first pour, moving the formwork and establishing the work cycle ensures that the site team uses the system correctly and efficiently. Rayf Teknik's aim is to develop metro tunnel formwork solutions for metro and tunnel projects that are safe, durable, reusable and fully matched to the project geometry.