Logan is the engineer who wins the drawing to drive the first John Galt Line train on opening day. An older company man, Logan is serious and devoted to his job, but he also has a very dry sense of humor:
"Mr. Logan, do you have any children? Did you take out any extra insurance? I'm just thinking of the bridge you know."
"Don't cross that bridge till I come to it," Pat Logan answered contemptuously. (18.104.22.168-20)
Logan definitely fits in well with the type of people Dagny likes and admires.
What's remarkable about his character, though, is that this once-devoted company man becomes part of the frozen-train phenomenon. He walks off the train Dagny is taking to Utah in an effort to stop Quentin Daniels from leaving. The fact that a man like Logan becomes a deserter is very telling about the state of the country and the lengths people would go to in order to survive.
It's also interesting that we see so many of the older Taggart Transcontinental employees, whom Dagny seems to prefer over the younger ones. This may be a way to demonstrate how the country's educational system has gone down the toilet. The young people we see are either relegated to menial jobs, like Quentin Daniels, or are shuffled into stooge positions in Washington, like the Wet Nurse. Logan is sort of the last of a dying breed.