What 397.7(b) means in plain language
FMCSR 397.7(b) prohibits you from parking a commercial motor vehicle carrying hazardous materials in any location that is not approved or designated for that purpose. In other words, hazmat loads have strict parking rules — you cannot simply pull into a rest area, truck stop, or roadside location and leave your vehicle unattended unless that specific location is authorized to accept hazmat cargo.
The rule exists because hazmat loads carry inherent risk. An unauthorized parking location may lack proper safety infrastructure, emergency response access, or oversight. If your vehicle is parked in a location where hazmat vehicles are not permitted, you are in violation regardless of how briefly you stopped or whether the cargo was properly placarded and secured.
This applies to any hazardous material as defined by the Department of Transportation — not just bulk liquids or gases, but also certain solids, oxidizers, and other regulated substances. Check your shipping papers and placards before you park.
What our enforcement data actually shows
Across our 13 million+ inspection records, 397.7(b) is one of the least-cited hazmat parking rules. Our database shows 22 all-time citations for this violation, with zero citations in the last 12 months and zero in the last 90 days. This places 397.7(b) at rank #1898 out of 3,036 FMCSR codes by citation volume.
Of the 22 all-time citations, none resulted in an out-of-service order — the OOS rate is 0.0%. This is a sharp contrast to the all-FMCSR average out-of-service rate of 31.4%, suggesting that when 397.7(b) is cited, inspectors view the violation as correctable at roadside rather than a safety-critical defect requiring immediate removal from service.
The virtual absence of recent enforcement (zero citations in 90 days) suggests that either this violation is rare in the field, or fleet and driver compliance has improved significantly. Either way, the low citation rate means fewer drivers are encountering this citation compared to other hazmat rules.
Who gets cited most
Our inspection records show a dispersed citation pattern. The top carriers cited for 397.7(b) each have only one citation in our all-time data: Rogers Cartage Co, Empire Gas Co Inc, Breckenridge Trucking Inc, American Petroleum Company Inc, Mason and Mefford, Western International Gas & Cylinders Inc, Asphalt Transport Inc, Gemini Motor Transport LP, W2 Logistic Inc, and Trimac Transportation Inc. No single carrier dominates this violation, indicating it is not a systematic compliance failure at any particular fleet.
Vehicle-wise, Freightliner (FRHT) units account for 6 of the 22 citations, followed by Kenworth (KW) and other miscellaneous vehicles (OTHR) with 3 each. Volvo, Heil, and a few other makes round out the list. The concentration in Freightliner suggests no particular make is exempt, but heavy-duty tractor-trailers — the most common hazmat carriers — naturally appear more often.
How severe is this compared to similar codes
397.7(b) sits in the Hazardous Materials category alongside many other parking and handling rules. To understand its relative weight, compare it to peer codes:
General loading/unloading violations (177.834A-HMC and 177.834(a)) are far more serious. Our data shows 3,954 and 3,839 citations respectively, with out-of-service rates of 99.2% and 97.9%. These codes involve improper handling of hazmat during the loading or unloading process — a direct safety event — and are almost always grounds for immediate vehicle removal.
Placarding violations (177.817(a)) also dwarf 397.7(b) in frequency: 2,274 citations with a 75.1% OOS rate. A placard that is missing, obscured, or incorrect means first responders may not know what cargo is on board in an emergency — a severe risk.
Maintenance of emergency response information (172.602(c)(1)) has 1,464 citations with a 0.0% OOS rate, matching 397.7(b)'s OOS profile. However, that code is cited far more often, suggesting parking location violations are genuinely rare.
The key insight: 397.7(b) is a compliance-and-location issue, not a cargo-handling or communication emergency. That is why it carries a 0.0% OOS rate — it is a violation of rules about where you may leave your vehicle, not about what happened to the cargo or whether emergency responders can identify it.
How to avoid it
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Know the authorized parking locations on your route before you depart. Contact your dispatcher or carrier safety team to confirm which truck stops, rest areas, or shippers along your route accept hazmat vehicles. Do not assume a large truck stop will take your hazmat load.
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Check your shipping papers and placards at every stop. Confirm you are actually carrying hazmat before you park. Sometimes paperwork changes or loads are swapped; a vehicle placarded for hazmat must use designated parking only.
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If you must stop unexpectedly (mechanical issue, fatigue, weather), contact your carrier or dispatcher immediately. Do not park in a random location. Your carrier can direct you to an authorized facility or provide guidance on a safe, legal alternative.
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Ask the shipper or receiver for parking instructions when you load or unload. They can tell you which parking areas are off-limits for hazmat and which are permitted. This is especially critical if you are new to a facility.
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Stay current on DOT hazmat rules. Your carrier should provide annual hazmat training. If you haul hazmat regularly, request a refresher on parking rules specific to your commodity class.