I wrote a lot about the cause down below.
credit to hannafanboy4ever, amtrakman4014, and blackshop-productions. rest in peace to all of the people that died in the disaster of the unmanned runaway. the reason there is no locomotive engine sounds is because, the locomotive stayed running in a siding while the engineer was at a hotel for the night. the lead locomotive was old and in need of repair, the reason that the train was left running was because of the air flowing to the airbrakes. but the locomotive caught fire because of the bad condition it was in. so the fire department arrived and put out the fire and shut off the train. but that stopped the air flowing to the air brakes causing the airbrakes to stopped working. the train slightly started rolling down the tracks. another reason is that the train needed a minimum of 9 handbrakes applied on the rolling stock, but only 7 were applied. in result the train rolled down the tracks and crashed in the town of lac-megantic. read more about it on Wikipedia or something.
