49 CFR 393.86: Rear impact guards

What the cited provisions say

Under 49 CFR 393.86(a)(2), the guard's horizontal member must extend to within 100 mm (4 inches) of each vehicle side extremity without projecting beyond it. Section 393.86(a)(3) limits ground clearance beneath that member to 560 mm (22 inches) across its width, allowing rounded corners to curve upward within 255 mm (10 inches) of the specified tangent planes at the vehicle sides.^{[1][2][3][4][5]}

At heights of 560 mm (22 inches) or more, 49 CFR 393.86(a)(4) places the member's rearmost surface within 305 mm (12 inches) of the vehicle's rear extremity, permits rearward projection beyond that extremity, and allows rounded corners to curve forward within 255 mm (10 inches) of the side extremity. Section 393.86(a)(5) requires a cross-sectional vertical height of at least 100 mm (3.94 inches) throughout the guard width. For guards governed by paragraph (b), 49 CFR 393.86(b)(2) instead expressly requires substantial construction and attachment using bolts, welding or comparable means.^{[1][2][3][4][5]}

Who and what the provisions cover

Section 393.1(a) limits part 393 to motor vehicles and combinations meeting the commercial motor vehicle definition. Section 390.3T(a)(1) states the general applicability to employers, employees and commercial motor vehicles transporting passengers or property in interstate commerce, subject to the exceptions in 49 CFR 390.3T(f). Section 393.1(e) separately excludes pipeline welding trucks as defined in its referenced provision.^{[1][2][3][4][5]}

Under 49 CFR 390.5T, gross vehicle weight rating is the manufacturer's maximum loaded weight for a single vehicle. The commercial motor vehicle definition in 49 CFR 390.5T requires highway use in interstate commerce and qualification through specified weight, passenger or hazardous-material criteria. Under the commercial motor vehicle definition in 49 CFR 390.5T, the weight criterion is a gross vehicle weight rating, gross combination weight rating, gross vehicle weight or gross combination weight of 4,536 kg (10,001 pounds) or more, whichever is greater. That definition in 49 CFR 390.5T has a different function from the trailer equipment threshold stated in 49 CFR 393.86(a)(1); the supplied pound values are retained separately.^{[1][2][3][4][5]}

Conditions and exceptions

Section 393.86(b)(1) excludes truck tractors, pole trailers, pulpwood trailers, road construction controlled horizontal discharge trailers and vehicles in driveaway-towaway operations. For otherwise covered vehicles, 49 CFR 393.86(b)(1) requires guards when the empty vehicle's rear body bottom edge, or chassis assembly if rearmost, is more than 76.2 cm (30 inches) above ground.^{[1][2][3][4][5]}

Section 393.86(b)(1)(i) requires installed and maintained guards to have empty-vehicle ground clearance no greater than 76.2 cm (30 inches). Section 393.86(b)(1)(ii) limits the nearest-point gap between multiple guards to 61 cm (24 inches). Section 393.86(b)(1)(iii) places the horizontal member's outermost surfaces no more than 45.7 cm (18 inches) from each vehicle side, while 49 CFR 393.86(b)(1)(iv) limits placement forward of the rear extremity to 61 cm (24 inches).^{[1][2][3][4][5]}

Under 49 CFR 393.86(b)(3), low chassis, special purpose and wheels back vehicles satisfy paragraph (b)(1) when constructed and maintained so that their body, chassis or other parts provide comparable rear protection. This conditional compliance route under 49 CFR 393.86(b)(3) is distinct from the exclusions in 49 CFR 393.86(a)(1).^{[1][2][3][4][5]}

Related provisions in the saved sources

Section 393.5 defines a road construction controlled horizontal discharge trailer as a trailer or semitrailer equipped with a mechanical drive and conveyor to deliver asphalt and other road building materials, in a controlled horizontal manner, into a lay down machine or paving equipment for road construction and paving operations. Under 49 CFR 390.5T, a driveaway-towaway operation transports an empty or unladen motor vehicle with one or more sets of wheels on the roadway between vehicle manufacturer facilities; between a manufacturer and a dealership or purchaser; between a dealership or other vehicle seller or lessor and a purchaser or lessee; to a motor carrier's terminal or repair facility for repair of disabling damage, as defined in that section, following a crash; to such a terminal or facility for repairs associated with vehicle component or system failure; or by saddle-mount or tow-bar.^{[1][2][3][4][5]}

Section 393.1(b) assigns compliance duties to motor carriers and employees, and applicable duties to intermodal equipment providers and personnel responsible for inspection, repair and maintenance of interchanged equipment. Section 390.3T(e)(3) requires all motor vehicle equipment and accessories required by the subchapter to be maintained in compliance with all applicable performance and design criteria set forth in that subchapter.^{[1][2][3][4][5]}

Source date and limits

The saved-source date for this entry is 2026-11-06. Its statute-only scope is limited here to the supplied federal regulatory text from the eCFR, attributed to the National Archives and Records Administration, Office of the Federal Register. It does not represent verification of the law on a later date.^{[1][2][3][4][5]}

Section 393.86(a)(1) references FMVSS No. 223 and FMVSS No. 224, but their substantive text was not supplied. Their detailed requirements are therefore outside this account. Likewise, references in 49 CFR 393.1(e) and 49 CFR 390.5T do not supply the omitted definitions or standards themselves. The saved materials support a reference description of the named provisions, not conclusions about judicial interpretation, fault, liability, insurance coverage or damages. This rear-guard entry provides general reference information rather than legal advice or a determination of how the provisions apply to a particular vehicle or incident.^{[1][2][3][4][5]}

See also

• FMCSA and federal trucking rules

On related publications

• Texas truck accident statistics (2020-2024) (truckaccidentlawyers.wiki)
• Georgia DPS adoption of federal motor carrier safety rules (atlantatruckaccidentlawyers.wiki)
• https://flanaganlaw.wiki/practice-areas/truck-accidents/ (flanaganlaw.wiki)