Hours of Service is the federal rulebook governing how long a commercial driver may be at the wheel, how long their on-duty window may run, and how much rest must be taken between shifts. It lives at 49 CFR Part 395, it applies to every property-carrying CMV regardless of cargo class, and it bites hardest on hazmat lanes — particularly Class 1 attended freight — because the rest-and-driving math collides directly with the continuous-attendance mandate of § 397.5. A shipper or dispatcher who does not understand the collision will misread their carrier's quote, misread the transit time, and misread why team-driver coverage is not an upsell.
The 11/14/70 framework
Part 395 lays out the basic property-carrying CMV rules in three numbers that every fleet manager committed to memory long ago.
- 11-hour driving limit. A driver may drive a maximum of 11 cumulative hours after 10 consecutive hours off duty. After the 11th hour, the driver must stop driving — full stop, no shipper-pressure exception, no almost-there grace.
- 14-hour on-duty window. The 11 hours of driving must fit inside a 14-hour on-duty window that starts when the driver first goes on duty after a 10-hour rest. After the 14th hour, the driver may not drive again until another 10-hour off-duty period is taken. The 14 keeps running whether the driver is driving, fueling, loading, waiting at a gate, or eating lunch.
- 70-hour cycle (8-day) or 60-hour (7-day). The carrier elects one of two duty cycles. Under the 8-day option, total on-duty time may not exceed 70 hours in any rolling 8-day period; under the 7-day option, 60 hours in 7. The cycle resets via the 34-hour restart provision when the driver takes 34 consecutive hours off duty.
These four limits — 11, 14, 70 (or 60), and the 10-hour reset — are the spine of Part 395. Every other provision in the part is either a refinement of one of those numbers or a documentation requirement that proves the numbers were observed.
The 30-minute break
§ 395.3(a)(3)(ii) adds a fourth interlock to the framework. After 8 cumulative hours of driving without an interruption of at least 30 consecutive minutes, the driver may not drive again until that 30-minute break has been taken. The break may be satisfied by any non-driving status — on-duty-not-driving, off-duty, or sleeper berth — so a driver who sits at a loading dock for 30 minutes after seven hours behind the wheel has satisfied the rule before the eighth hour even begins.
The break exists to address fatigue accumulating in a single driving stretch and is independent of the 11-hour and 14-hour limits. A driver may have hours of driving and on-duty window remaining and still be illegal to operate the vehicle if the 30-minute break has not been logged.
The split-sleeper-berth provision
A driver running a sleeper-equipped tractor may split the required 10-hour off-duty period into two segments rather than taking it as a single continuous block. The current rule allows a 7/3 or 8/2 split: one segment of at least 7 (or 8) consecutive hours in the sleeper berth, paired with a second segment of at least 2 (or 3) consecutive hours either in the sleeper or fully off duty. Either segment may come first; together they satisfy the 10-hour rest requirement and reset the 11-hour driving and 14-hour window clocks.
For team-driver Class 1 attended freight, the split-sleeper provision is operationally significant. A team running a 600-mile leg can use the longer segment for the deeper rest and the shorter segment to absorb a fueling stop, a terminal wait, or a routing diversion without burning the entire 10-hour reset. Continuous attendance is maintained by the off-driver because the on-driver is awake, out of the sleeper, and within the § 397.5 attendance envelope while the resting driver banks segment hours.
Where § 395 collides with § 397.5
The collision is the central operational fact of Class 1 long-haul.
A single driver running a Division 1.1, 1.2, or 1.3 explosives load is governed simultaneously by Part 395 and § 397.5. Part 395 mandates a 10-hour off-duty rest, almost always taken in a sleeper berth at a truck stop or rest area. § 397.5 forbids that rest unless the vehicle is parked on motor-carrier, shipper, or consignee property, in a designated safe haven, or in a duly posted area. The driver cannot legally satisfy both rules at once on most lanes — the supply of safe havens between Atlantic Coast ports and inland destinations is finite, route-dependent, and frequently nonexistent on the lanes a customer actually needs to run.
The result is binary. Either the load runs with team-driver coverage, where one driver attends the vehicle while the other rests in the sleeper and the § 397.5 attendance envelope is maintained continuously, or the route is replanned around safe havens for every required reset and the schedule penalty is absorbed. For most ammunition, explosives, and DOD freight, lane geometry makes the second option impractical. Team-driver coverage is therefore not a service tier — it is the operational consequence of two federal rules that cannot both be satisfied any other way.
Hazmat-specific exceptions
There is no hazmat exception to Hours of Service. The rules are the same 11/14/70 the general property-carrying fleet runs under. What changes for hazmat is the layer of additional constraints that surround the same HOS clock.
§ 397.5 mandates continuous attendance for Division 1.1, 1.2, and 1.3 freight. § 397.7 imposes parking restrictions — distance from public structures, distance from places of habitation, and approved-area requirements — that reduce the set of locations where a hazmat driver may legally take a rest break. § 397.67 and § 397.101 impose routing restrictions that frequently force the driver onto longer routes than the unrestricted equivalent, eating into the 11-hour driving budget. The interaction is one of constraint, not exemption. A hazmat driver runs the same HOS clock as any other CMV driver, but with fewer legal places to spend it.
ELD compliance per Part 395 Subpart B
Subpart B of Part 395 — § 395.20 through § 395.38 — governs the electronic logging device. Every CMV operating under HOS records duty status on an ELD, with narrow exceptions for short-haul operations (§ 395.1(e)) and certain pre-2000-model-year vehicles. A placarded hazmat load, by virtue of being on an HOS-regulated CMV, runs the same ELD requirement as any other CMV. There is no hazmat-specific ELD provision; there is only the general rule, applied without the short-haul carve-outs that some commercial fleets rely on.
Auditor edge cases live in the elections a carrier makes. The 8-day vs 7-day cycle is a carrier-level election that must be applied consistently and recorded. The short-haul exemption at § 395.1(e) — which permits a paper time record in lieu of an ELD for drivers operating within a 150-air-mile radius and returning to the work-reporting location within 14 hours — is a frequent compliance trap on hazmat lanes, because a driver who runs a 200-mile drayage to a customer dock and back has exceeded the radius and forfeited the exemption for that day. Auditors look for the day the exemption was claimed in error, not the days it was claimed correctly.
What this means operationally
For a fleet manager, dispatcher, or hazmat shipper trying to read their carrier's quote, three operational facts follow directly from the rules above.
- Team-driver coverage on Class 1 OTR is not a line item the customer can negotiate away. It is the operational consequence of HOS and § 397.5 on lanes longer than a single 11-hour clock. A carrier quoting single-driver service on a 1,200-mile attended-freight lane is either misquoting or planning a non-compliant operation; neither answer is acceptable to a defense buyer or a commercial buyer with insurance to renew.
- "Save money on a single driver" does not work for attended freight. The savings on the second driver are notional. The carrier either runs team-driver and absorbs the cost, runs single-driver and absorbs the schedule penalty of safe-haven planning, or runs single-driver illegally and absorbs the audit risk. None of those is a saving the customer wants on their record.
- Integrated operators that own the OTR leg solve this directly. When the same carrier owns drayage, transload, holding, and long-haul under one USDOT, the HOS and § 397.5 calculation is built into the dispatch decision before the load leaves the port. Team-driver assignments, reset locations, restricted-route avoidance, and ELD compliance are the same operating discipline applied across every leg, not four independent vendor decisions stitched together by a broker who never sees the cab. Ramar's long-haul defaults to team coverage for Class 1 attended freight for exactly that reason — the math says so, and the integrated chain absorbs the cost without resetting the documentation at every handoff.
The 11/14/70 framework is the background fact of every hazmat lane. The team-driver requirement is the foreground consequence on attended freight. Any quote, transit estimate, or carrier capability conversation that does not reckon with both is an incomplete one.