A History of Federal Trucking Underride Standards

Table of Contents

    We have known about the dangers large vehicles like 18-wheelers, dump truck, Mack trucks and others present to a much smaller, everyday passenger vehicle. Regardless of whether the motorist is driving a compact car, a sedan, a pickup truck or even an SUV the commercial truck dwarfs the passenger vehicle. While the danger is most pronounced in vehicles that sit close to the ground that can, therefore, run under the truck. Combined with the truck’s significantly greater mass when the vehicles crumple zones and impact absorbing features are rendered ineffective, more severe injuries follow.

    Understanding how these standards came about can help inform our understanding about gaps in its protections. Furthermore, it can be informative in guiding our expectations regarding the future development of and improvements to the standard.

    The Development of the 1953 Under-Ride Standard

    Since at least the early 1950s, we have recognized the underride risks posed by large trucks. Thus, in 1953 the first federal standard regarding truck under-ride guards was passed. These 1953 standards applied to both a straight-truck vehicle type and to a truck trailer. These standards mandated that both of these vehicle aspects have an under-ride guard that met certain criteria. These criteria included a when the distance from the truck’s cargo bed to the ground exceeded 30 inches. This measurement was to be taken while the truck was completely unloaded and perpendicularly from the ground. This standard also included exceptions from the under-ride standard for a number of vehicles. Exempted vehicles included:

    • Pulpwood trailers
    • Any vehicle where the cargo bed in lower than 30 inches
    • Tractors
    • Any vehicle with equipment attached to the back that could act as a guard
    • Pole trailers
    • Tow trucks and flatbed drive-way trucks
    • Any vehicle where the rear of the tires is less than 24 inches from the end of the vehicle’s cargo body

    While strength requirements for the guards were not defined in this standard, it did require them to be bolted or welded to the vehicle or trailer. Other requirements of the under-ride guard provided by the standard included:

    • At the rear-most portion of the vehicle (within 24 inches of the back), the clearance from the bottom of the guard to the ground can be no greater than 30 inches.
    • The guard must cover an area within 18 inches of the vehicle sides.

    For straight-trucks, the 1953 standard is still the controlling law. Likewise, it also governs the safety of covered trucks produced prior to January 26, 1998. However, it is also important to note that recommendations for enhanced requirements for under-ride protections were made by the US DoT after the grisly 1967 death in a truck accident by celebrity Jayne Mansfield and the public concern that followed.

    The Understanding the Changes that Make Up the 1998 Under-Ride Standard

    The federal safety standards for underride protection devices were updated in 1998. The new updated standards applies only to trailers & semitrailers that were manufactured after January 26, 1998. These changes were codified in Federal Motor Vehicle Safety Standards 223 and 224. FMVSS 223 focuses on the installation of the underride guard. FMVSS 224 focuses on the strength and testing standards for the guard.

    These changes to FMVSS 223 and 224 focused on three primary areas of concern:  guard height, the rear wheel guard dimensions, and cargo bed height. As for guard height, the 1998 revisions reduced the permissible height to 22 inches. The wheel guard dimensions, previously set at 24 inches from the end of the cargo body, were reduced to 12 inches. Finally, the height standard for truck cargo bays was also reduced to 22 inches.

    While these changes likely expanded the scope of protection and the number of trucks covered, the law also exempted many vehicles. Exemptions included many of the vehicles previously listed above, and also included the exemptions for special purpose vehicles, per 49 CFR S 178. Under the standard special purpose, vehicles are defined as those vehicles equipped with work performing equipment or gear that is mounted to the vehicle and located in the area where an under-ride guard would otherwise be installed. Similarly, the exception also applies if a rear lift-gate would perform a substantially similar function.

    How Will Under-Ride Standards Continue to Evolve?

    While more than 40 years passed between major revisions to under-ride standards, it is unlikely that such an extended delay in updating standards will reoccur. In fact, there are signs that federal regulators will update and strengthen under-ride standards in the near future. In the next articles in this series, we will examine some of the potential amendments that will strengthen these standards and some of the problems with the current under-ride rules.

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