Technically, they are not. Amtrak is structured as a corporation. The federal government owns all (or nearly all) of the stock in the corproation, but Amtrak employees are employees of the corporation, not the federal government.
Under the Amtrak Reform and Accountability Act, damages paid by the government to people injured in Amtrak derailments and families of those passengers killed was limited to $200 million per crash.
This country has so many problems....I fear for my kids...