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VARIOKIT, the adjustable formwork for tunnel projects supplied by PERI
Products, services and expert advice for your next tunnelling project.


Tunnel construction requires collaboration between many teams due its complexity. Projects usually require the input of geologists, specialists for earthworks, foundation and ground engineering and road construction, structural engineers, concrete technologists as well as planners for transport and operational safety.

Among this group of specialists, we have gained an international reputation as a reliable partner, supporting our customers with high-quality formwork and scaffolding systems and providing expert advice when required.



Types of construction and cross sections

Tunnel cross-sections and lengths should be the main consideration when deciding which construction method and supporting framework to use.

In addition to this, there are object-related curves and inclinations along the tunnel as well as varying geometries in width and height that have to be considered. Variations in the standard cross-section are necessary for the purpose of park and emergency stop bays, escape and access galleries or for constructions that link adjacent tunnel tubes with another.

Our approach to tunnel construction supports the four methods below:

  • open-cut tunneling 
  • mining method
  • cut-and-cover method
  • special and supplemental types of construction

Cross-sections can be rectangular, round, elliptical or a designed according to special requirements. A simple rectangular cross-section is the most cost-effective manufacturing option. However, depending on the framework conditions, circular, elliptical or special cross-sections can offer specific advantages.




Supporting frameworks in tunnel construction

Regardless of the construction method, a number of different supporting frameworks can be used depending on the cross-section, geological conditions and the future use of the tunnel. Each tunnel framework can be single-cell or multi-cell.



Overview of PERI tunnel construction solutions


Open cut tunneling: interrupted cross-section.

As with regular high-rises, the floor, walls and slab of the tunnel cross-section are produced independently.

Framework conditions

  • Cycle lengths of up to 30 m
  • Clear height ca. 3 m to 10 m
  • Clear width according to structural restrictions
  • Number of cycles: max. 10

Open cut tunneling semi-monolithic.

Walls and slab are concreted in one pour. Their production takes place with two separately moving, structurally autonomous formwork carriages.

Framework conditions

  • Cycle lengths up to ca. 25 m
  • Clear height ca. 4 m to 10 m
  • Clear width ca. 4 m to max. ca. 20 m per carriage
  • Number of cycles min. ca. 10 up to max. ca. 60 cycles

Open cut tunneling semi-monolithic.

Floor and walls are concreted in one pour. Because of its absolute water-tightness, this construction method is mainly used in groundwater areas.

Framework conditions

  • Cycle lengths up to max. 15 m
  • Clear height ca. 4 m to 8 m
  • Clear width ca. 25 m
  • Number of cycles min. ca. 10 up to max. ca. 60 cycles

Open cut tunneling monolithic.

Floor, walls and slab are concreted in one pour. Due to the minimum amount of joints, high water-tightness of the whole tunnel cross-section is achieved.

Framework conditions

Variant with launching beam:

  • Cycle lengths min. ca. 10 m to max. 24 m
  • Clear height ca. 3 m to ca. 10 m
  • Clear width max. ca. 20 m
  • Number of cycles min. 50 cycles

Variant with portal and rear carriage:

  • Cycle lengths min. ca. 10 m to max. 20 m
  • Clear height ca. 4 m to ca. 9 m
  • Clear width max. 18 m
  • Number of cycles min. 25 cycles


Mining method.

Tunnel is built underground. The excavation for the circular or oval cross-sections is done either by blasting or with tunnel drilling machines.

Framework conditions

  • Short distances: Arched formwork is combined with shoring
  • Medium distances: Use of horizontally movable system formwork carriages
  • More than 60 concreting cycles: automated use of arched formwork carriages

Cut-and-cover method.

Construction with minimum traffic disruptions. With this construction method, excavation only reaches up to the bottom edge of the future tunnel slab.

Framework conditions

  • Cycle lengths up to ca. 30 m
  • Clear height up to max. 12 m
  • Clear width without restriction
  • Number of cycles from 1 cycle

Deviations from the standard cross-section.

Necessary changes of the standard cross-section due to parking and emergency stop bays, escape and access galleries, etc.

Framework conditions

  • Formwork carriage adjustable to cross-section changes with minimum additional work 
  • Unimpeded formwork change between standard and deviating cross-sections possible 

Transition tunnel / above-ground area

Transitional structures link above-ground traffic routes with the underground routing.

Framework conditions

  • The shape and dimensions of formwork geometries can be flexibly adjusted to the topography and landscape. 
  • Surface finish of the portal walls can also be flexibly formed.

Gallery-type structures / half-open structures.

Half-open tunnels with single-sided or overhead light. Galleries can be independent structures or longer transitional structures.

Framework conditions

  • Technical design and production analogous to construction methods which are tried and tested in tunnel construction
  • Suitable for all PERI formwork and scaffolding systems which can be used for tunnel construction.

Maintenance of tunnel structures.

Construction-related measures for the maintenance, partial renewal or modification of existing tunnel structures.

Framework conditions

  • System components can be used for all types of tunnel construction mentioned above
  • Thorough damage analysis while considering the technical and organizational necessities 
  • Maintenance and process planning conform to the generally applicable rules and regulations.

Work phases in tunnel construction

We provide products and services for every phase, from construction to maintenance to tunnel refurbishments and repair, helping you deliver your project from planning to completion as efficiently as possible.

Project cause

  • New construction
  • Maintenance / repair
  • Maintenance / refurbishment

Planning phase

  • 2D- / 3D-planning
  • Defining the formwork system
  • Defining the formlining
  • Defining the construction sequence
  • Creating the logistics concept

Forming phase

  • Erecting the formwork
  • Adjusting the formwork
  • Moving the formwork
  • Dismantling the formwork

Concreting phase

  • Providing / distributing of concrete
  • Inserting of concrete
  • Compressing of concrete
  • Curing of concrete


Application variations second to none: The VARIOKIT engineering construction kit

The VARIOKIT engineering construction kit can be used without any limitations in tunnel and bridge construction and civil engineering. This essential customer benefits are the result of high-degree standardisation and the possibility to combine the system components, which are based on just three core elements:

  • SRU steel waler
  • RCS climbing rail
  • SLS heavy-duty spindle

This means that the VARIOKIT engineering construction kit consists of about 80% standard components and only the remaining 20% are object-specific, adjusted special parts. On top of this, the possibility to rent the PERI standard components reduces the rate of tied-up investment capital.


Featured Projects

Our products have been used on a variety of tunnel projects all over the world. Below are some examples from PERI UK.

Products and services for your Tunnelling project

From innovative moving scaffold systems and bespoke plywood panels to 3D drawings and digital engineering software, we can provide the products and services you need to complete your project.

More detailed information

Tunnel Formwork Technology Manual

All topics mentioned above are explored in more detail in our Tunnel Formwork Technology manual. In addition to explaining specific tunnel construction methods in detail, the manual also refers to many successful projects that we have worked on and provides commentary about how we met the customer's requirements.






Tunnel Formwork Technology Manual



160 pages of valuable expert knowledge.


<<< Click here to download >>>