What 397.7B means in plain language
397.7B addresses where you park a commercial truck carrying hazardous materials. The regulation prohibits parking your vehicle in locations that are not authorized for hazmat transport. This isn't about how you load or secure the cargo—it's about choosing the right location to stop or park.
Authorized parking spots for hazmat vehicles are typically designated by state and local authorities. They're often located away from populated areas, schools, hospitals, and other sensitive locations. When you're transporting hazmat, your choice of parking location directly affects public safety. Parking in an unauthorized area—whether overnight, during a meal break, or to address a mechanical issue—violates this requirement.
What our enforcement data actually shows
Across our 13 million+ inspection records, 397.7B is an exceptionally rare citation. Our database shows only 10 citations all-time, with 2 in the last 12 months and 0 in the last 90 days. In June 2025, we saw 2 citations.
The most striking finding: none of the 10 citations resulted in an out-of-service order. The OOS rate for 397.7B is 0.0%. By comparison, the all-FMCSR average OOS rate is 31.4%, meaning this violation is enforced at a much lower severity threshold than most other hazmat codes. Ranked #2191 out of 3,036 FMCSR codes by citation volume, 397.7B appears infrequently in roadside enforcement.
Who gets cited most
Our inspection records do not provide state-level breakdowns for this code. However, the carriers cited include Coastal Transport Co Inc, Servicios Especializados Alanis SA de CV, Transportes Especializados Antonio Garza Ruiz SA de CV, Gas Cylinder Services, USA Logistics Inc, and several owner-operators. Each of these entities had one citation in our database.
Vehicle types cited include freight trucks, pickup trucks, and utility vehicles, suggesting this violation occurs across multiple hazmat transport configurations.
How severe is this compared to similar codes
397.7B sits in a distinct enforcement bracket compared to other hazmat regulations. General loading and unloading violations—codes 177.834A-HMC and 177.834(a)—generated 3,954 and 3,839 citations respectively, with OOS rates of 99.2% and 97.9%. Placarding violations (177.817(a)) resulted in 2,274 citations with a 75.1% OOS rate.
In contrast, 397.7B's 0.0% OOS rate aligns more closely with other structural hazmat requirements like 172.516(c)(6) (placard condition, 1.6% OOS) and 172.602(c)(1) (emergency response information, 0.0% OOS). This suggests enforcement officers treat parking location violations as technical infractions rather than immediate safety threats requiring vehicle removal.
How to avoid it
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Plan your route and stops before departure. Identify truck stops, rest areas, and designated hazmat parking facilities along your route. Use your GPS or TruckCodex mapping tools to locate authorized parking ahead of time, not while fatigued or running behind schedule.
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Know the rules in each state. Hazmat parking restrictions vary by state and county. Before entering a new jurisdiction, confirm where you're legally permitted to park. Call ahead to truck stops if you're unsure whether they accept your commodity.
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Never park on city streets, residential areas, or near schools and hospitals. Even if a spot looks convenient, if it's not explicitly designated for hazmat, don't use it. When in doubt, stay at a certified truck stop or contact your dispatcher for guidance.
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Document your authorized parking locations. Take a photo of signs marking hazmat parking areas at trusted stops. If cited, evidence that you parked in a marked zone can support your defense.
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Address mechanical issues at authorized facilities only. If your truck breaks down and needs repair, call for a tow to a truck service center or authorized hazmat-friendly facility. Do not park at an unauthorized location while waiting for roadside assistance.