Andy wants a job as a signalman on the

railways. He is told to meet the inspector at the signal box. The

inspector puts this question to him: “What would you do if you
realised that
two trains were heading for each other on the same
track?”
Andy says, “I would switch the points for one of the
trains.”
“What if the lever broke?” asked the inspector.
“Then I’d dash down
out of the signal box,” said Andy, “and I’d
use the manual lever
over there.”
“What if that had been struck by lightning?”
“Then,”
Andy continues, “I’d run back into the signal box and phone
the
next signal box.”
“What if the phone was engaged?”
“Well in that
case,” persevered Andy, “I’d rush down out of the box
and use the
public emergency phone at the level crossing up there.”
“What if
that was vandalised?”
“Oh well then I’d run into the village and get
my uncle Silas.”
This puzzles the inspector, so he asks, “Why
would you do that?”
Came the answer, “Because he’s never seen a
train crash.”