Keep those TBMs moving

New contractors are entering the tunnel boring sector, where the role of field service is responding with dramatic changes to keep TBMs operating. One of history's epic civil engineering works, the Channel Tunnel is perhaps the most famous of all TBM projects. The Transmanche-Link JV excavated north- and south-running tunnels, as well as a service tunnel, using 11 TBMs six from the UK side; five from France. The 39km undersea drive across the English Channel was known to include fractured and faulted chalk with high potential for water inflows. Hard rock was not the only challenge for the project, however. In October 2009, the machine at the inlet site was a week away from launch when a once-in-a-century monsoon hit the region. Challenges began with abrasive rock that increased consumption of cutters and conveyor belt components at the outlet site.