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[oldestguy]

I figure you all might want to examine the photo on Geotech Other site. I managed to freeze the TV shot. Seems like the driller's aim was good between the two rails.

 

[BigHarvey]

Ihave seen something similar in Lille (France) where a CFA piling rig did a hole for a piezometer which was not programmed initially. The hole was outside the original piling zone. It went through the subway tunnel underneath and a train collided the string. No death but a few people wounded !

 

[BigH]

These must be some mighty powerful drills!

 

[oldestguy]

Big H:

Actually these days with the carbide cutting tools, drilling through concrete for bridge borings is a regular occurrence. At abutments and mainly where piers will go, drilling through slabs or the deck happens all the time. I would bet the driller figgured "Gosh a buried old basement". Maybe he then went on down into the roadbed.

I recall a boring in Milwaukee where the PL was supposed to be 5 feet from a buried city fire alarm system cable. So they stayed more than 5 feet from the usual PL locations. When the DOT crews pulled up an obstruction, it was a large coil of copper wire wound around the bit. Turns out the PL was in the center of the sidewalk, very unusual. Kinda expensive fix that.

 

[BigH]

Yeah, maybe you are right but really, wouldn't the driller have an inkling? or the engineer logging the boring?