Which signals may be used to warn of a stopped vehicle which contains explosives?

• A. Reflective triangles
• B. Flares
• C. Radio whistles
• D. Flags

Answer: (A)

Warning other drivers when a vehicle containing explosives is stopped should be done with reflective warning devices. Reflective triangles are designed to be highly visible from a distance in daylight and at night, helping approaching traffic slow down and steer away from the hazard. They do not create ignition risks, which is crucial near explosives.

Flares pose a real ignition hazard due to open flames or sparks, making them unsuitable in this scenario. Flags may offer some daylight visibility but aren’t reliable at night and aren’t the standard, regulated warning device for HazMat stops. Radio whistles aren’t used as traffic warning signals.