What special precaution must a driver take when approaching a railroad crossing while hauling certain hazardous materials, particularly those requiring placards?

Correct answer to question 175 (Hazardous Materials): Stop before the tracks as required, check both directions, and cross only when it is clearly safe to do so

Why

Certain vehicles, including many carrying hazardous materials, are required to stop before railroad crossings, check carefully in both directions, and proceed only when it is clearly safe, given the serious consequences of a collision involving hazardous cargo.