Pros
The pay for the work that your "required" to do is good.Lots of veterans work at Union Pacific. You get a lot of downtime to do homework, sleep, or whatever else as long as you don't get hurt.
Cons
This is a family business at the shop I work at, meaning if you are to move up in the company you better have a close friend or relative up the chain somewhere. The hours and days you will be working the first 10-20 years of your employment will not be desirable. If you wind up with a schedule that works for you it is likely management will force you to change jobs. You are just a number on a seniority roster. The turnover rate is astronomical. Management is terrible. No one has a clue what is going on 99% of the time. If someone doesn't want to work that day the lower seniority guy is going to get screwed over while the guys that have been there a while go hide from management. The training is nearly non existent and they only take 4 people at a time once every few months. So expect to no how to do your job after about 12 years. But by then you'll have forgot everything and conformed to the railroader mentality. Also the trainer at our shop was employed by the railroad for less than 3 months before his promotion, but his uncle works at UP head quarters so they had to give him the job. Troubleshooting a locomotive at up is unheard of. You will change parts upon an idiots gestamation. No skill at all is required for this job. I'm not sure why they even have a pre employment for electricians to determine there intelligence. And how some people pass the test is beyond me.