OK, I stand corrected in that Amtrak Police officers are not federal law enforcement officers but are more like railroad police officers commissioned by a state.

THAT SAID...federal law grants railroad police officers that are commissioned in one state to have authority in any other state the railroad operates. Thus, if a crime occurs on, say, the Coast Starlight Amtrak Police would still have much greater latitude to investigate; whereas a local police officer would have no jurisdiction once the train crosses state lines (or beyond the limit established by the state in which the train entered).

From Amtrak Police's career website:

[police.amtrak.com]

Certificate of completion of a basic training program at a state authorized police training academy or current related experience as a police officer or similar law enforcement experience preferred. An Associate’s Dgree or 60 hours/credits from an acccredited college or university preferred.

Able to obtain a police commission within the state in which assigned or in state of residence.

Why Amtrak Police officers aren't just federal law enforcement officers, who knows. Despite the Postal Service also being a government sponsored enterprise, Postal Inspectors are very much federal law enforcement officers. (Then again, there are no laws specific to Amtrak unlike postal crimes.)

Oregon law regarding railroad police:

ORS 131.880: Appointment of railroad police officers; liability. The Governor, upon application of any railroad company operating in this state, may appoint and commission, during the pleasure of the Governor, persons designated by the company and to serve at the expense of the company, as police officers, with the powers of peace officers and who, after being duly sworn, may act as police officers to protect the railroad company property and the persons or property of the railroad company passengers or employees. The railroad company designating such persons is civilly responsible for any abuse of their authority.

ORS 810.550: Authority of railroad officers to move illegally parked vehicles. When a regularly employed officer of a railroad commissioned to act as a police officer by the Governor under ORS 131.880 finds a vehicle parked or standing upon any railroad track or within seven and one-half feet of the nearest rail in violation of ORS 811.555, the person may move the vehicle, cause it to be moved or require the driver or person in charge of the vehicle to move it to a position more than seven and one-half feet from the nearest rail.

Federal law regarding railroad police (49 CFR 207):

[www.gpo.gov]