Warning devices: Responding to an accident or breakdown
Even the safest driver operating under the best conditions can encounter an accident or breakdown on the road. What’s important is that your drivers know what to do and what to expect to make sure they can safely and legally deal with the situation.
TIP: Show your drivers examples of the type(s) of warning device(s) carried on your vehicles. Make sure they know where devices are stored in the event of an accident or breakdown.
Where do warning devices go?
When a vehicle is stopped on the traveled portion or shoulder of the highway, the driver must immediately activate the vehicle’s four-way flashers. Drivers must also set out warning devices as soon as possible. The regulations require they be set out within 10 minutes of stopping.
When placing the devices, the driver should hold them in front of themselves to increase visibility to traffic while wearing a high-visibility vest. Remind drivers to stay alert to other drivers who may not see them on the road.
The placement of devices will vary depending on where the vehicle is stopped:
Two-lane road
- The first device should be placed on the traffic side of the vehicle 10 feet (4 paces) from the front or rear, depending on traffic direction.
- The second device should be placed 100 feet (40 paces) behind the vehicle.
- The third device should be placed 100 feet (40 paces) ahead of the vehicle on the shoulder or in the lane where the vehicle is stopped.
One-way or divided highway
• Devices should be placed 10, 100, and 200 feet from the rear of the vehicle, toward approaching traffic.
Within 500 feet of a hill, curve, or obstruction
• A device should be placed 100–500 feet from the vehicle in the direction of the obstruction.
•The other two devices should be placed according to the rules for two-lane or divided highways, whichever best applies.
TIP: Drivers are often surprised to see how far 100 feet is when illustrated by a vehicle and warning devices. Demonstrate correct placement by taking your drivers outside to see the correct setup. Set devices in the correct spots around one of your vehicles that’s parked on site.
Don’t forget the requirements
Section 393.95 of the Federal Motor Carrier Safety Regulations (FMCSRs) requires a commercial motor vehicle (CMV) to carry:
• Three bidirectional emergency reflective triangles, or
• At least six fusees capable of burning for 30 minutes.
Other warning devices may be used in addition to the required warning devices, provided the alternative warning devices don’t decrease the effectiveness of the required warning devices.
Fusees or any other signal produced by a flame aren’t allowed on:
• Any vehicle 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) hazardous materials whether loaded or empty; or
• Any CMV using compressed gas as a motor fuel. ♦
TIP: Select a video to help introduce this topic, making sure you consider your drivers’ experience and the types of emergency situations they may deal with while on the job.
Provided by J.J. Keller & Associates
To view the full monthly newsletter click here: Warning Devices July 2026
