system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 Why do school buses stop and open the door at railroad tracks?
gpt
During a whiteout blizzard in December 1st, 1938, a school bus driver Slim Silcox was driving 39 students in the town of Sandy, Utah.  

Silcox decided to drive over a railroad crossing that has never had any train traffic during his normal school pickup hours. However, because of the weather conditions, he did not see or hear a train that was driving on the tracks because the train was delayed from it's normal schedule. The train T-boned the bus and killed 24 students instantly including Silcox. 3 students died later from their injuries.

Because of this incident, buses are required to stop before rail crossings and look and hear for any oncoming trains. Since then, there have not been ~~any~~ many severe collisions. Many regulations are written in blood.

Edit: People have mentioned other bus/train collisions since this one.