Tunnel vision in the Middle East

14 of the 21 Herrenknecht TBMs have now arrived in Qatar
Herrenknecht has delivered 14 of the 21 earth pressure balance tunnel boring machines which will be used for Doha metro.

When I was asked to write about the tunnelling sector in the Middle East as part of MEED‘s construction coverage I was excited by the prospect of covering some of the biggest underground metro contracts in the world at the moment. Gulf markets may be small in population terms but in tunnelling terms the use of 21 TBMs simultaneously boring new tunnels for Doha metro for example makes it one of the largest projects ever undertaken. At the same time TBMs are burrowing new sewer lines on the Abu Hamour project and Qatar is also working on a new deep sewer tunnel, replicating similar schemes undertaken in Abu Dhabi, Singapore and London.

However as I dug deeper I found myself drawn to some of the smaller and less well known projects, which are nevertheless having a massive impact on the region’s infrastructure. New sewage, drainage, water supply and district cooling systems are using trenchless pipe placement to install modern infrastructure beneath cities and if microtunnelling were a fashion, it would be gracing the cover of Vogue.

“The Middle East is probably the most active market in the world for microtunnelling at the moment,” Chris White, managing consultant at Bahrain based Target Trenchless told me.

Microtunnelling itself tends to be used on smaller diameter tunnels than the kind of mechanised tunnelling with tunnel boring machines (TBMs) used for roads, bridges and other major infrastructure schemes. Although there are many similarities between the methods there are some important differences. “The main difference between microtunnelling and using a TBM is that with microtunnelling you are pushing a pipeline into place behind the microtunnelling machine, but with a TBM you are building the lining in place behind it,” said John Wheeler, general manager at Al Naboodah Specialist Services, part of the Al Naboodah Construction Group.  Other characteristics of microtunnelling include the fact that the face of the excavation is supported during the dig and the machines are usually remotely operated (not manned).  As the pipes are jacked into place behind the head the method is also sometimes referred to as pipejacking.

I was also fortunate enough to talk to experienced contractors about their experiences delivering some of the schemes that were already underway. It became pretty clear that tunnelling and microtunnelling are complicated, challenging and that the ground conditions are EVERYTHING! The full report is online at MEED here

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