Driver Tips: Warning Devices And What To Do

Even the safest driver, operating well-maintained equipment, may have to deal with a breakdown or accident at some point in his or her career. 

Warning Devices: Know What To Do, Original article written by PacLease

Knowing what to do when the unexpected happens can help in legally and safely dealing with an accident, breakdown or emergency situation. Keep reading to learn about best practices and tips for using your warning devices. 

Warning Device Placement

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 and within ten minutes, set out warning devices. Placement of the devices varies depending on where the vehicle is stopped. 

On a 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.
  • A 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.

On a one-way or divided highway, the 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 to 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.

When placing the devices, the driver should hold them in front of himself or herself to increase visibility to traffic. He or she should wear a high visibility vest if possible and be alert for other drivers who may not see him or her on the road.

Warning Device Requirements

  • Section 393.95 of the Federal Motor Carrier Safety Regulations (FMCSRs) requires a commercial motor vehicle (CMV) to carry at least:
  • Three bidirectional emergency reflective triangles
  • Six fuses capable of burning for 30 minutes
  • Three liquid burning flares that contain enough fuel to burn continuously for at least 60 minutes

However, note that flame producing devices are not 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
  • Any CMV using compressed gas as a motor fuel


When an accident happens, immediate action is necessary. The driver should:

  • Stop immediately
  • Remain calm and pull the vehicle as far off the road as possible
  • Turn on the vehicle’s four-way flashers and set out warning devices
  • Notify law enforcement
  • Check for injuries
  • Document the accident
  • Notify his or her motor carrier
  • Complete a preliminary report

When documenting the accident, the driver should include:

  • The time and location
  • A description of damage
  • The names and addresses of all people involved
  • The names and addresses of the insurance companies of the people involved
  • The type, make, model, and license numbers of all vehicles involved
  • The names and departments of investigating officers

The driver should always be polite and respectful, keeping in mind that anything said at the accident scene could be used against the driver and/or the motor carrier at a later date. The driver should never:

  • Discuss specific details with others
  • Volunteer unnecessary information
  • Admit fault
  • Try to settle anything at the scene

The driver should:

  • Honestly answer questions asked by law enforcement
  • Be factual, but never speculate or guess as to what may have caused the accident or who is at fault

Accident Report Kit

In addition to carrying the required warning devices, an accident report kit should be in the vehicle, so all the items needed to document the accident are available in one place. The kit should include:

  • A high-visibility vest
  • A written report form to help document the accident
  • A diagram template for completing a simple drawing of the accident scene
  • Witness cards
  • Pens/pencils
  • A camera

Vehicle breakdowns

When a breakdown occurs, the driver must:

  • Safely stop and secure the vehicle
  • Turn on the vehicle’s four-way flashers
  • Set out emergency warning devices

The driver must contact his or her motor carrier, and provide:

  • The location of the breakdown

A description of what happened including odd sounds or smells, vehicle handling issues, and any other information that may be important to the person performing the repairs.

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