If drivers are on duty but not driving after the 14th hour, have they used the 16-hour short-haul exception in 395.1(o)?

No. For example, if the driver of a property-carrying commercial motor vehicle was on duty 16 hours on Wednesday but didn’t drive after being on duty 14 hours, the driver could use the 16-hour extension on Friday and be allowed to drive after the 14th hour as long as all other conditions and regulations (11-, 16-, and 60/70-hour rules) were met. In this scenario, the driver may choose to use the 16-hour extension on Friday as long as the driver meets all of the requirements for the 16-hour exception outlined in 395.1(o) and also remains in compliance with 395.3(a) and 395.3(b). Although the 16 hours on duty on Wednesday will count toward the driver’s 60/70-hour calculations, the driver has not utilized the 16-hour exception unless the driver has actually driven after the 14th hour.