Most of us who work with landslides have on occasions had to work on drilling – dangerous, dirty, difficult to deal with – and that’s just the drillers! One of the most difficult problems is knowing where the drilling head is actually going. In this context there is an extraordinary story that I found through GeoPractNet, on a The Local, a Swedish news site, from 11th December:

Driver in shock as drilling crushes subway train
The red line in Stockholm’s subway was stopped for one hour on Thursday after a work team’s drilling punctured the subway tunnel and damaged a train.

The work team was drilling at Wollmar Yxkullsgatan, on Södermalm, to prepare for the installation of geothermal heating for a nearby hotel, but their drilling punctured the subway line and crushed the side panels of the driver’s carriage of a train that was waiting on the tracks. “They drilled right down onto a subway train,” Lars-Erik Baarsen, station officer at Södermalms Police, told news agency TT. After the workers had drilled to a depth of 20 to 25 metres, the team noticed that the resistance to the drill disappeared. “They then withdrew the drill and discovered that two-and-a-half metres of the drill was missing,” Baarsen said. Meanwhile, down in the tunnel, the driver of the subway train was shocked when the side panel of his carriage was suddenly crushed by something from above.

Fortunately the driver was unhurt. Of course this is not quite as spectacular as probably the greatest drilling rig error of all time, the extraordinary 20th November 1980 Lake Peigneur accident in Louisiana (read the link – you won’t regret it), but it is quite amazing.