Stopping a CMV: Overview And Observations

Stopping a CMV: Overview

While state “rules of the road” may address stopping of any motor vehicle, the dangers created by the stopping of a large truck were sufficient to motivate the authors of the FMCSR to implement detailed and specific requirements to warn oncoming traffic. In considering these requirements, the reasons for a stop must also be analyzed. State law may prohibit stopping in the “emergency” lane for any but specified reasons. If the driver has stopped to study a map or take a nap, he may be in violation of not only the FMCSR but state law as well.


1. When a CMV is stopped on the “travelled portion” of a highway or on the shoulder for “any cause other than necessary traffic stops” the driver must immediately activate the “vehicular hazard warning signal flashers,” commonly known as “4-ways,” and use them until other warning devices described below are placed, and then again while those warning devices are being collected and stowed prior to resuming travel.

2. As soon as possible after stopping, “but in any event within ten minutes” a driver must place warning triangles, lit flares or lit fusees. On a two lane road, three such devices shall be placed, one “4 paces” (three meters or ten feet) in the direction of oncoming traffic, one 40 paces (thirty meters or one-hundred feet) in the direction of oncoming traffic and one 40 paces in the direction away from oncoming traffic. The devices must comply with the requirements for emergency equipment set forth.

3. If the driver uses flares or fusees, he must make sure he keeps burning ones in place while stopped.

4. If daylight, the warning devices must be placed within ten minutes. This subsection does not include the requirement the devices be placed “as soon as possible” for a daylight stop– just within ten minutes. Thus, expect a motor carrier defending an accident which occurred during daylight hours, defined as “the period lighted lamps are not required”, to argue that the “as soon as possible” requirement described at No. 2., above, does not apply.

5. If the stop is in a “business or residential district”, warning devices need not be placed except during times when “lighted lamps” are required if no street lighting is sufficient to make the CMV “clearly discernable” at a distance of 500 feet.

6. On a hill, curve or obstructed area, the warning device must be placed “in the direction of the obstruction to view a distance of 100 feet to 500 feet from the stopped CMV”.

7. On a divided or one lane road, the warning devices shall be placed ten feet, one-hundred feet and two-hundred feet in the direction of oncoming traffic.


Horrific accidents have occurred because drivers of CMV have failed to place warning devices. If you handle such a case, you must be ready to examine the driver on the exact sequence and timing of his stop, the accessibility of the devices, his training regarding placement and why the devices were not placed when the accident occurred. It may be tactically advisable not to mention the devices until you have gone over in detail each action of his upon stopping and his best recollection of how long each action took.
For example, if he stopped because of a mechanical problem, looked at the manual to see what was wrong with the truck, sent a Qualcomm to his motor carrier, called a wrecker/tire truck/mechanic, called his wife, updated his logs to reflect a stop (he may have wanted to have his logs up to date in case the police looked at them during the stop) he may have used over ten minutes, and in any event, would be outside the “as soon as possible” sphere of time. In this way, you may have the driver pinned to a version which places him in violation of the regulations before the subject ever comes up.
Note that the requirement is presented for any stop other than “necessary traffic stops.” If the driver is involved in an accident, he must place the warning devices. A small accident may easily turn deadly because no warning device was used. No exception is given when, for example, the police are there immediately. You are likely to encounter a proximate cause argument in that case, but the rule provides no exception. What constitutes a “necessary traffic stop” is not defined. Depending upon the facts of the accident, you may have some room to argue except in a clear case, i.e., traffic stopped.
Note also the requirement regarding the proximity of the warning devices to the truck, if they were placed. If they were not properly placed the question will likely become whether this caused on-coming traffic to be unable to spot and react to the truck in time to avoid an accident. You will likely need a conspicuity expert in that case, and be ready for a proximate cause argument from the defense. Expect the motor carrier’s lawyers will have done a re-creation to show that the vehicle was visible for hundreds of feet, even without the devices. You must be ready to counter this argument and evidence with your own expert testimony and, possibly, re-creation of the accident.
You must discern whether this was a “business or residential district”, and if so, whether there was sufficient street lighting to avoid the warning device requirements. Both terms are defined, and the definitions are fairly precise. Make certain you are not dealing with an area where no warning devices were required before pinning your case, and possibly your money in the form of a conspicuity expert’s fee, to the absence of warning devices. Of note, a limited access freeway shoulder is not within either definition. The same goes for a hill/curve/obstruction, where the placement of the devices may need to be altered to address the terrain/structure issues.
Further, be prepared to address the absence of the “as soon as possible” admonition when the accident occurred during daylight hours. One question, not addressed by the FMCSR—What about the accident which occurs in the rain, when state law requires that vehicles activate headlights? The regulation specifically references “daylight hours”, so arguing a driver is required to place triangles “as soon as possible” because it is raining is going to be an uphill fight. Consider arguing the “extreme caution” requirement as requiring triangles be placed “as soon as possible.”

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