Collecting some thoughts:
I believe Mr. Norman made a comparison of 6 hour flights with 50 hour train rides. I don't find this comparison at all apt. For one thing: flight attendants can work multiple shifts and up to 18 hours a day (and in most cases are only paid for the time the doors to the plane are closed. So if they're stuck at the terminal gate with the door open for 2 hours due to a delay, they're not necessarily getting paid. And on the flip side, the vast majority of my Amtrak travels have been either ALB-NYP or NYP to points beyond (generally preceded by a ALB-NYP leg). This means day trains where the crew is either flipping and sleeping in their own bed at the end of the night, or generally the next night. the point being they're not on the train for 50 hours or more. Of course on LD trains you have the OBS folks how may be there for that long). But in either case, I don't think actual service hours should matter.
Someone else mentioned the conductor's principal job is train safety and I don't deny that. However, flight attendants are also responsible for safety and while in-flight they are primarily in the customer service business, a very important part of their job is still safety. Besides the aforementioned safety videos, they're also making sure items are secured, folks seated in exit rows can perform their duties, aiding in evacuations if necessary, and of course dealing with irate passengers. So in terms of crew duties, they're a bit more similar than I think some give credit to.
Also mentioned was sending folks to training and not punishing. Generally I agree. Rarely does "punishment" result in a better employee.
I mentioned corporate culture and I'm reminded of a recent change at my alma mater: RPI here in Troy. The outgoing president, Dr. Jackson had an impressive set of credentials and she accomplished a lot while here, including a massive infrastructure expansion plan. By some metrics she was very successful. But, morale SUCKED. There were many reasons. The new president has already improved morale. He's started at the top. First of all, he insists on going by his first name. Some may not like such informality, but after over two decades of a president who NEVER EVER let you forget her title and all her credentials, it was a refreshing change. His first week on campus he went to the book store to buy himself a sweatshirt and politely inquired about the employee discount. This was in contrast to the former president who, as far as anyone knows never stepped foot in the bookstore and almost certainly sent staff in her place (and knowing her personality made sure the staff would insist on the employee discount). She also surrounded herself by people similar to her. I had an encounter with the VP of Communications. One of the most arrogant, condescending people I've met in a professional setting. But that was the tenor. I haven't met the new VP of Communications, but the student I talked to (who had also met the previous one) said he was much friendlier, outgoing and open to dialog.
Overall, employees are MUCH happier and students are happier.
The point of this is that you really do need it to come from the top.
Now someone else mentioned consistency. I have to agree, though I'd couple this with both flexibility and having a clear rational. I think Amtrak is fairly close to this, but could get better. Have, as much as possible, consistent goals for boarding. But, allow flexibility. If an employee allows a passenger to board in the wrong place, roll with it and then the conductor can talk to the employee privately. ("Hey Joe, I know you let the customer board in the cafe, but that just messed up my boarding. Try not to, but if you do, just let me know as soon as you can".) Don't take it out on the passenger.
I'm rambling now, but overall:
Start form the top. Make it clear what the tone should be.
Try to be consistent, but allow for flexibility and if there's a problem, handle it privately and discretely.
When given the choice between enforcing a rule and making a customer happy, as long as safety is not involved, make the customer happy.
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