Investigations
Semi-Trailer Side Underride Guards
NHTSA Defect Petition DP24004 — closed, opened 2024-08-26.
NHTSA investigation DP24004 is a Defect Petition opened on 2024-08-26 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 2025-03-28 — NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Defect Petition like DP24004 starts when a person or group formally asks NHTSA to investigate a specific alleged defect. Petitioners submit evidence, NHTSA reviews it within 120 days, and either grants the petition (opening a PE) or denies it with a written explanation in the Federal Register.
Investigators summarized the matter as follows: "The Office of Defects Investigation (ODI) received a petition from Eric Hein, Director of the Institute for Safer Trucking dated July 3, 2024, requesting an investigation of all van-type (also known as box) semi-trailers..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time.
Investigation Summary
The Office of Defects Investigation (ODI) received a petition from Eric Hein, Director of the Institute for Safer Trucking dated July 3, 2024, requesting an investigation of all van-type (also known as box) semi-trailers due to collisions with passenger vehicles and other vulnerable road users (pedestrians, bicyclists, or motorcyclists) resulting in significant injuries or death due to the lack of side underride guards (SUGs). On August 26, 2024, NHTSA opened Defect Petition DP24004 to evaluate the petitioner’s request. No trailer manufacturer or equipment supplier was identified as the specific subject of the petition. The petition itself can be reviewed at NHTSA.gov under ODI Number 11599188. Currently, a Federal Motor Vehicle Safety Standard (FMVSS) requiring side underride guards on semi-trailers does not exist. The petitioner contends that a failure to include side underride guards equates to a safety defect in the semi-trailer’s design, construction and performance. ODI was petitioned in 2021 for this same issue and, after evaluation, denied the request (DP21004). The petitioner here states that evidence of SUG effectiveness to prevent fatalities and mitigate serious injuries “has continued to accumulate” since the denial of DP21004. The petitioner also alleges that “[d]espite a high severity of risk resulting in frequent severe or fatal injuries from side underride crashes, NHTSA has taken no action to investigate recalling semi-trailers without SUGs.” Pursuant to the Infrastructure Investment and Jobs Act (IIJA), NHTSA published an Advanced Notice of Proposed Rulemaking that summarized and requested comment on a 2022 NHTSA report with an analysis of potential effects of a requirement for side underride guards on new trailers and semitrailers. 88 Fed. Reg. 24536 (Apr. 21, 2023). NHTSA’s Office of Rulemaking is currently reviewing over 2,000 comments received. Also pursuant to the IIJA, on June 18, 2024, the NHTSA-facilitated Advisory Committee on Underride Pr
About This Investigation Type
A Defect Petition (DP) is initiated when an individual or organization formally petitions NHTSA to investigate a potential safety defect. NHTSA reviews the petition and decides whether to open an investigation.
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. Learn more.
Read our methodology — how this data is sourced, computed, and verified.