Hazards created by large commercial trucks stopped on the roadside
49 C.F.R. § 392.22 requires that when a commercial motor vehicle stops on a highway or shoulder, the driver must active hazard warning signal flashers, and within ten minutes must place either flares or bidirectional reflective triangles.
If the vehicle is stopped within 500 feet of a curve, hillcrest or other view obstruction, warning devices must be places so as to provide ample warning.
This regulation supports liability, and occasionally even punitive damages, when a motorist crashes into a stopped tractor trailer in poor visibility conditions.