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All commercial motor vehicles (CMVs) operating in interstate commerce must be equipped with devices that can be used to warn other drivers of the presence of a stopped CMV along the road.
Scope
These requirements apply to CMVs operating in interstate commerce.
Regulatory citations
- 49 CFR 392.22 — Emergency signals; stopped commercial motor vehicles
- 49 CFR 393.95(f) — Warning devices for stopped vehicles
Key definitions
- Commercial motor vehicle (CMV): A self-propelled or towed motor vehicle used on a highway, in interstate commerce, that meets any one of the following criteria:
- Has a gross vehicle weight rating (GVWR) or gross combination weight rating (GCWR), or gross vehicle weight (GVW) or gross combination weight (GCW), of 10,001 pounds or more, whichever is greater; or
- Is designed or used to transport more than 8 passengers (including the driver) for compensation; or
- Is designed or used to transport more than 15 passengers (including the driver), and not used to transport passengers for compensation; or
- Is transporting hazardous materials of a type or quantity which requires placarding.
Summary of requirements
A CMV must be equipped with either:
- Three bidirectional emergency reflective triangles,
- Six solid-fuel flares (fusees), or
- Three liquid-burning flares.
The driver must set out emergency warning devices within 10 minutes if the CMV is stopped on the traveled portion or the shoulder of a highway for any cause other than necessary traffic stops.
The placement of warning devices varies according to a variety of circumstances:
| Road type | Device placement |
|---|---|
| Two-lane road | On the traffic side of the vehicle 4 paces (about 10 feet) from the front or rear, depending on traffic direction. Also, place a device 40 paces (about 100 feet) behind and a device 40 paces (about 100 feet) ahead of the vehicle on the shoulder or in the lane the vehicle is in. |
| Within 500 feet of a hill, curve, or obstruction | 100 to 500 feet from the vehicle in the direction of the obstruction. Place the other two according to the rules for two-lane or divided highways. |
| One-way or divided highway | 10, 100, and 200 feet of the rear of the vehicle, toward the approaching traffic. |
Exceptions. Flame-producing devices are prohibited on:
- Vehicles carrying Division 1.1, 1.2, or 1.3 (explosives);
- Any cargo tank motor vehicle used for the transportation of Division 2.1 (flammable gas) or Class 3 (flammable liquid), whether loaded or empty; or
- Vehicles using compressed gas as a motor fuel.
If gasoline or any other flammable liquid, combustible liquid, or gas seeps or leaks from a fuel container or a CMV stopped upon a highway, flame-producing warning signals may only be placed at a distance from the liquid or gas that will assure the prevention of a fire or explosion.
The placement of warning devices is not required within the business or residential district of a city, except when street lamps are required or when the street or highway is insufficient to make a CMV clearly visible to people on the highway from a distance of 500 feet.