CMV Law: Parts & Accessories For Safe Operation


49 CFR Part 393 discusses “[p]arts and accessories necessary for safe operation” of a CMV. The regulations therein provide explicit instructions about many of the components that fit together to make up a CMV. Prompt inspection of a vehicle, particularly in a case where no obvious reason for a collision is apparent, is important. For this reason, counsel is advised to send a letter to the motor carrier requesting that the vehicle be preserved – without repairs or alteration of any kind – until there is an opportunity to inspect it. If the client does not retain counsel until after the vehicle has already been repaired or disposed of, then discovery of any inspection conducted by the motor carrier, either by an expert or shop mechanic, is the best available substitute. Even if the vehicle has been disposed of, counsel should attempt to find out what yard it was sent to; it may still be sitting there, even months after a crash.
It is also important to obtain any report prepared by authorities that documents any inspections of the vehicle. Either or both the state or federal DOT may have inspected the vehicle at some point. Their inspection report may have noted vehicle deficiencies that designated it (or should have) to be placed out of service. Some of these problems may have been a consequence of the incident itself, and thus not a factor for you. However, matters such as measurement of tire tread, brake pad thickness, and the like, documented by a government official charged with investigating the condition of the vehicle, oftentimes at the actual scene, can be worth their weight in gold.
Note that the regulations establish “minimum” standards for CMVs. In a given case, it may be possible to show that some characteristic of the operation required more rugged equipment. In any case, a “minimum” standard would not seem to establish a safe harbor by which a motor carrier can argue for summary judgment on the grounds that no negligence can exist upon technical compliance with the regulation. Further, “every motor carrier and its employees must be knowledgeable of and comply with the requirements and specifications” of Part 393. No driver should be permitted to get away with saying he did not know that the regulations required, for instance, a working horn. Note also that while many of the regulations pertaining to parts and accessories refer to a “motor vehicle,” that term is oddly not one of the over 80 terms defined within Part 393. However, elsewhere in the regulations, a “motor vehicle” is defined in pertinent part as “any vehicle, machine, tractor, trailer, or semitrailer,”and there is no reason to think this broad definition does not apply to the usage of the term in Part 393.
Be aware that the regulations addressing CMV parts and accessories incorporate by reference many authoritative engineering reports on various components of CMVs. These materials “are hereby made a part of the regulations in Part 393.” In a case involving a part or accessory defect or failure, this list should be reviewed to see if the particular part is the covered by one of these publications. If so, the publication should be obtained and studied. After all, because the regulations officially adopted the publication by reference, it more or less has the force of law. The more educated counsel can become, the better you he or she can interact with their expert – and deal with the opposing expert.

Lights and Reflectors: Overview

The rapid and steady transportation of cargo through interstate commerce means lots of night driving for CMVs. A 10,000+ pound CMV moving down the interstate at 55 miles an hour at night is even more dangerous to other motorists if it is poorly-lit and inconspicuous. Obviously, a massive tractor-trailer requires more illumination at night than a family sedan. With this consideration in mind, subpart B of Part 393 sets forth regulations governing lamps, reflective devices, and electrical wiring.
Numerous articles have been written about conspicuity and motor vehicle collisions. For a particularly good discussion, see T.J.Ayres, R.A. Schmidt, R.A. Schmidt, B.D. Steele, & F.P. Bayan “Visbility and Judgment in Car-Truck Nighttime Accidents” Safety Engineering and Risk Analysis, Vol. 4, ASME 1995. If a case involves a night-time wreck, conspicuity is almost certainly going to be an issue. Inspection and analysis of the reflective striping and the lights on a CMV will be an important part of the investigation. An expert may need to inspect the bulbs on the vehicle to determine whether at the time of impact the lights, by evidence of “hotshock,” or not, by “coldshock.” Notably, newer trucks may incorporate use of LED (light-emitting diode) technology, which is not as susceptible to damage as ordinary filament bulbs. There is a possibility that the manufacturer may have failed to properly design the vehicle with required markings, or that the markings may in some way have created an optical illusion that the vehicle was shorter or angled differently than was actually the case, such as to deceive an oncoming motorist into running into the vehicle.
An accident reconstruction with an exemplary vehicle with markings and lighting similar to those in use at the time of a crash may be worthwhile. Considerable care must be used to ensure the results are capable of being admitted into evidence or for use as a demonstrative aid. Therefore, much research should be done before the test is performed. Few things are more dismaying than the last-minute exclusion of a test that would have made the case, especially given the time, energy, and expense that went into setting it up and performing it.

Lights & Reflectors

1. The Regulations provide detailed information on the location of lamps and lighting devices, including diagrams of the required location and color of lamps and reflective devices.

2. All required lamps must be capable of being operated at all times and shall not be obscured by the vehicle’s tailboard, load, dirt or other vehicle or work equipment.

3. The regulations include illustrations showing the proper locations and positions for lamps and reflective devices on many types of vehicles, from ordinary box trailers to concrete mixers. See 393.11, Figures 1-18. These illustrations may be helpful in expert deposition or as demonstrative aids at trial.

4. The regulations reference 49 C.F.R., also known as Federal Motor Vehicle Safety Standard (FMVSS) No. 108. (“Lamps, reflective devices, and associated equipment”)

5. Certain requirements for reflective devices apply to trailers manufactured after December 1, 1993. Other requirements for retroreflective sheeting and reflex reflectors govern all trailers manufactured before December 1, 1993.The time within which a motor carrier was required to re-fit such trailers with retroreflective sheeting and reflex reflectors ran over a decade ago,(“Motor carriers operating trailers … have until June 1, 2011, to comply with the requirements of this section.”), and an accident involving a vehicle not so equipped would be unusual at this date. The regulations pertaining to older trailers do not mandate that those trailers be retrofitted with devices which meet FMVSS No. 108, as is required for trailers manufactured after December 1, 1993. However, motor carriers are explicitly “encouraged” to follow FMVSS No. 108. If they choose not to do so, they must nevertheless comply with the requirements, which describe the placement of the devices in detail.

6. Hazard warning lights on a CMV must work even when the ignition is turned off, and when activated, the hazard lights must cause all turn signals to flash simultaneously.

7. Standards are specified for headlamps, which are required, and auxiliary or fog lamps, which are not.

8. In some cases, the aiming of the headlamps may become an issue, and that, too, is a subject of FMVSS No. 108 along with specified SAE publications.

9. Note that while reflex reflectors are specified, the use of additional retroreflective surfaces may be used, § 393.26 but these must not create designs which “resemble traffic control signs, lights or devices.” However, straight-edge striping resembling a barricade may be used. Any additional markings must not tend to distort the length or width of the vehicle, and markings must be at least three inches from any required lamp or reflector unless the two are the same color. Red may not be used on the front of the vehicle except in certain limited circumstances.


The technical specifics of many issues pertaining to lamps and markings are not addressed here, as this is neither a technical discussion nor a diagram of every regulatory nuance. Rather, the central aim of this section is to assist counsel in identifying the prospect of a conspicuity-related accident while offering guidance regarding how to investigate the CMV involved to determine whether some breach of the regulations arguably caused the underlying incident. Once again, an expert may also be needed to tie the breach to the wreck for purposes of establishing proximate cause.

Pertinent Case Law

In Clark v. Bilkin, a Utah district court recently denied a motor carrier’s motion for summary judgment after finding that the potential violation of regulations requiring functioning lights created a jury issue on punitive damages.There, the 1960 trailer was found to have numerous inoperable lights. Discovery had revealed that approximately seven months before the incident, the defendant got a citation for, among other things, missing and inoperable lights, and had no reflective tape on the back. The court looked back at the regulations in force in 1960, and found the trailer was deficient. The court also noted the requirement that trailers manufactured before December 1, 1993 had to be retrofitted with reflective tape, and found that this had not been done with the subject trailer. Notably, the court also found the driver’s conduct in fleeing the scene and lying to law enforcement relevant on the issue of punitive damages.

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