Tunnel boring machines (TBMs) are a major focus of attention as one of the main methods of tunnel excavation and they are also mighty sights when being built and then employed on underground projects, but they can only come to be there and perform their tasks with the support of significant transport ability, lifting capacity and conveyor capability.

Whether on sites within congested large cities or coastal zones, or in open but rolling countryside or farther afield in high, harsh and remote mountainous environments, the TBMs need significant transport endeavours and then assembly power to get prepared and set to bore, getting their main work underway.

And, when underway, what they muck out needs to be efficiently and effectively removed from the TBM face, often by conveyor.

TBMs on tunnelling projects are supported by major lifting capacity and conveyor capability T&T looks at a few of the recent sights of TBM lifting and conveyors on major tunnel projects: ­

  • The Herrenknecht machine and logistical support for the Hampton Roads-Bridge Tunnel (HRBT) Expansion project, in Virginia, in the US ­
  • One of the machines being moved between drives on HS2 project, in the UK ­
  • Various vertical conveyors in shafts and use of TBM ‘first time’ assembly on some projects with Robbins equipment.


Here, on these pages, there is the lift of the large cutterhead for the single variable density TBM that will drive twin tunnels between islands for the HRBT project, and shafts.


One of the mighty sights of an illuminated disc on the move during the night in the English countryside last year was that of the giant cutterhead for the TBM ‘Dorothy’ on HS2’s Long Itchington Wood Tunnel.

After breakthrough on the first drive, the TBM’s main front sections were lifted, carefully and securely, onto specialist heavy duty transport to be taken back to the launch point. The large pieces were transported by road and through a village.

The 10m-diameter cutterhead weighs 160 tonnes. It was moved standing upright on a 12m-long, 48-wheel self-propelled trailer (SPT). On a 4km-long (2.5-mile) journey. At night.

The Herrenknecht TBM’s 120-tonne tail skin was moved in the same operation.

Eight other large pieces from the front and middle shields were transported separately beforehand.

Once the pieces were back where tunnelling began at the north portal, the machine was reassembled for the second drive. The TBM backup train had been moved separately – pulled back along the built tunnel by a special ‘caterpillar’ system, at a pace of 150m per day.

Dismantling and transporting TBM ‘Dorothy’ was an intricate, 24/7 operation, managed by the plant and logistics team at HS2’s contractor Balfour Beatty Vinci (BBV).


A challenge solved in mucking out from tunnel works – and still quite a sight to see – is a conveyor carrying the spoil vertically up and out of a shaft.

It is also a significant feat to engineer TBM systems such that the parts are lifted and first come together, fully, through its Onsite First Time Assembly (OFTA) system, when preparing for earnest operation on a project site.

One of the projects where Robbins supplied an extensive conveyor system was the DigIndy tunnels below Indianapolis, IN, in the US. Another use of the vertical conveyor belt transfer system was moving out mixed ground during tunnelling works at Mexico City’s Emisor Oriente tunnel project.

 Beyond vertical conveyors as part of package systems, the company has supplied in-tunnel and stacker conveyors for many projects – such as the in-tunnel conveyors that travelled behind its Crossover TBM on the Kargi hydro project, in Turkey; and, the stacker conveyor for depositing spoil at the AMR water tunnels, in India.

On OFTA, Robbins has supplied the system on a number of tunnelling projects, such as on the Black River Tunnel in Lorain, Ohio.

The OFTA system takes place by assembling major components in a concrete cradle. The system has been successfully used to save months on project schedules, and also benefits projects by reducing shipping costs and man-hours compared to the option of shopassembled machines, says Robbins.