[DuncanWaring]

...some sort of switch or lever ...

Yeah. It's called a "Deadman's Pedal". If it isn't being stepped on, the train is supposed to stop.

Apparently they don't always work.

[A. Patriot]

Yeah. It's called a "Deadman's Pedal". If it isn't being stepped on, the train is supposed to stop. Apparently they don't always work.

Maybe it was disabled?????

Had a brick or something else heavy on it???

Just idle speculation.

[tractorman]

Deadman’s pedals were disconnected years ago.

Back in the ‘70’s I worked as a brakeman for the CMSP&P and they were disconnected back then.

One time, in the middle of the night, we actually hit our own train.
We left 80 cars parked on the main line and were backing 20 cars and four locomotives into the yard, or so we thought. Unfortunately, the new kid threw the spring switch the wrong way and sent the train back to me. I hopped on the last car and was riding back into the yard when I saw our train right in front of me.

I gave the new kid a “washout” signal to relay to the engineer, but instead of him relaying it, he threw his flare down and jumped. When I saw that, I jumped too and watched as the front half crashed into the rear half. The impact was so great that it shifted the car bodies of the locomotives off their frames and catapulted the engineer through the back door out onto the catwalk. It took 10 hours to clean up the mess.

That was just one of many incidents.