"Signalman's Quiz" joke

Ed was applying for a job as a signalman for the local railroad and was told to meet the inspector at the signal box.
When they met, the inspector decided to give Ed a pop quiz. "What would you do if you realized that two trains were headed towards each other on the same track?" the inspector asked.
"I would switch one of the trains to another track," answered Ed.
"What if the lever broke?" asked the inspector.
"Then, I would run down to the tracks and use the manual lever down there," a confident Ed replied.
"What if that lever had been struck by lightning?" the inspector challenged.
"In that case," Ed continued, "I'd run back up here and use the phone to call the next signal box."
"What if the phone was busy?" the inspector asked.
"Well, then I would run to the street level and use the public phone near the station," Ed argued.
"What if it had been vandalized?" inquired the inspector.
"In that case I would run into town as fast as I could and get my Uncle Bert," Ed stated.
This really puzzled the inspector, so he asked, "Why on earth would you do that?"
"Because he's never seen a train crash!"