There is no federal regulation to prevent an engineer or conductor (or other railroad employee covered by the Hours of Service Act) from working the kind of extreme hours Had8ley talked about. The only restrictions are (1) a maximum of 12 hours on duty at one time, (2) 8 hours rest required after less than 12 hours on duty, and (3) 10 hours rest required after 12 hours on duty. An employee can also work "short-rested", for instance working 5 hours, then getting 4 hours rest, then eligible to work the balance of the 12 hours. It's not uncommon for crews to tie up one minute short of the 12 hours, showing 11'59" on duty, so that they won't be "penalized" the extra 2 hours rest. Excepting vacation periods, an employee could literally work 7 days a week year-round so long as the proper 8- or 10-hour rest periods are taken.
As the Railroad Retirement Board bases one's retirement pay on, IIRC, the highest 3 years' earnings of the last 5 years of service, it's not unusual for one to work much harder than normal in order to boost the monthly pension amount. That sounds very much like what Had8ley was doing.....he'll correct my assumption if it's incorrect, of course. Generally speaking, anyone with his seniority in the same craft, with the same railroad, could pretty much "coast" into retirement if they chose to.
As far as Amtrak's engineers and conductors, if they are working a regular job with assigned rest days, they don't get anywhere close to the extreme scenario. Life is more hectic for those on the extra board but, IIRC, even they have at least one assigned rest day per week.
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For more on the Hours of Service (Title 49, Part 228, The Code of Federal Regulations), go to
http://www.utu.org/depts/RESEARCH/HOURSOF.HTM