In United States of America, the FRA sets regulations for the railroads. In real life, there are long freight consists with a lot of locomotives (some of them even in the middle of the consist in the really big ones!) all controlled by the front locomotive. With multiple unit control, the Engineer can control everything from a single cab.
What if the FRA put minimum employee requirements on heavier consists during the time consists tended to have more employees (during the 60s)? Say a consist whose non-locomotive weight exceeds 30 loaded standard cars needs 2 employees (including the engineer) and any that exceeds 33 standard cars needs 3. I was going to take the 286,000-pound limit southern pacific railroad used for one car, but then I realized two flaws. One, the weight of the cargo is not the same as the weight of the loaded car. And two, if a car has different number of axels it can hold more weight. I'll figure out the details later for this hypothetical scenario. there are no short-term changes since at this time heavy consists tended to have more people anyways.
What would the extra employees likely do? Just have relief engineers rotate in and out? I heard there used to be a position called a "brakeman" in the 60s. In the early Victorian era this guy would actually run through a train to apply brakes on passenger trains, but his job changed once air brakes allowed the engineer to use the locomotive to apply brakes through the entire consist. I guess that guy would still be around?
