what vehicles must stop at all railroad crossings
Here is what vehicles must stop at all railroad crossings answer for beginner drivers appearing in the Dmv test.
what vehicles must stop at all railroad crossings?
All passenger vehicles, school buses with or without children, and cargo vehicles with explosive substances or inflammable liquid must stop at all railroad crossings. The only reason not to stop is if a police officer or traffic stop signal directs traffic to proceed.

However, if you are appearing in the Dmv test then you may face what vehicles must stop at all railroad crossings in your written test.The examiner will give you certain options and you have to select one option as your answer as above.
Explanation of what vehicles must stop at all railroad crossings:
According to Federal Railroad Administration USA, passenger, school, and cargo vehicles with explosive material must stop at all railroad crossings. Whether these vehicles are with passengers or without passengers and loaded or empty. These vehicles have to stop at all uncontrolled railroad crossings. More importantly, these vehicles must stop within fifty feet but not less than fifteen feet from all railroad crossings.