Two provisions move the limits rather than replace them. Under § 395.1(b)(1), a driver who encounters adverse driving conditions as § 395.2 defines them, and who cannot because of those conditions safely complete the run within the maximum driving time or duty time permitted under § 395.3(a) or § 395.5(a), may drive for not more than TWO additional hours beyond the maximum allowable — to complete that run, or to reach a place offering safety for the occupants and security for the vehicle and its cargo. Two points decide whether it applies. Adverse driving conditions is a defined term, not a general judgment about weather. And the relief is an extension of two hours, not a suspension of the rules: everything else continues to apply.

§ 395.1(b)(2) is broader and rarer. In case of any emergency, a driver may complete the run without being in violation of this part, if the run reasonably could have been completed absent the emergency. The condition in that sentence does the work — the question is whether the run was achievable within the limits but for the emergency, not whether an emergency occurred.

Finally, a driver moving between freight and passenger work changes envelopes entirely. § 395.5 sets different limits for passenger-carrying vehicles: no more than 10 hours driving following 8 consecutive hours off duty, and no driving for any period after having been on duty 15 hours following 8 consecutive hours off duty. The weekly limits are the same 60 hours in any 7 consecutive days or 70 in any 8, on the same carrier-operation test. Note the shape of the difference: 8 hours off rather than 10, 10 hours driving rather than 11, and a 15-hour on-duty limit that is measured differently from the property-carrying 14-hour window. Nothing about the property rules carries across. How any of this is recorded — on paper or by electronic logging device — is Chapter 8’s subject.