Megashor can be used in challenging tunnelling projects

In several past blogs we have written about how strong and versatile some of the propping systems we work with are. We would like to further highlight this by discussing the unique work that took place to create the Farnworth Tunnel. It is a project that all Megashor temporary installers should look at.

Engineering on the original Farnworth Tunnel was complete in 1838. It became an important part of the Manchester to Bolton line. A second bore was complete in 1880 to allow Down trains with Pullman carriages to use the route. Re-engineering on the first tunnel subsequently restricted use to Up trains.

Upgrade to the infrastructure

More recently there was a project to electrify the trains in the North West. Unfortunately both of the existing tunnels couldn’t accommodate the infrastructure because of lack of space. The solution was to create a new one.

The work to bore a new tunnel was immensely challenging. The contractors were effectively embarking on a unique job. There were therefore no guides to follow. The excavating equipment was practically a prototype.

Utilising Megashor

Several issues occurred on the project during excavation including with the shield for the tunnel. At two points material from above flowed into the tunnel. One of them resulted in settlement on the surface, increasing the load on the shield. Ultimately, it was necessary to reduce the pressure using propping. The decision was to use Megashor props.

At one point a 14mm ground movement was detected, triggering an alert and ceasing train operation. An examination was necessary to determine the issue. It found that the Megashor frames were under increased distress. As a result, backfilling had to be completed quickly.

The tunnel was completed successfully and has become an essential piece of the transport infrastructure. The project shows how great propping systems are, even when called on to handle retaining huge weights in tricky settings.

If you would like help from highly experienced Megashor temporary installers please contact us. Denon Construction is an accomplished team with a wealth of knowledge. We work in many tricky settings and strive to produce great results.