What would the trucking industry look like without 70 percent of the independent and small-fleet owner-operators moving freight today? What if 52 percent of company drivers and leased owner-operators at larger fleets also suddenly exited the business?   A special report on the potential impact of a proposed federal rule requiring electronic logging devices (ELD) to be used in most large trucks to track driver hours of service answers those questions and more. The report cites a recent reader survey by Overdrive, a national trucking magazine, in which a majority of respondents said they would retire or look for other work before they’d operate with an ELD.     Under the proposed rule by the Federal Motor Carrier Safety Administration, ELDs could be mandated for virtually all interstate haulers by late 2016. Many large and medium-sized fleets have already adopted ELDs or are phasing them in, while many of the smallest fleets are holdouts.   It’s unclear how many truckers would follow through on threats to quit, but those who do will make a tough situation worse: If the 71 percent of independents with from one to five trucks actually did quit, the industry would lose about 260,000 trucks, according to RigDig Business Intelligence.  That removes more than 10 percent of the industry’s capacity. When the 71 percent includes carriers with up to 15 trucks, it reduces capacity by more than 27 percent, or around 709,000 trucks. The American Trucking Associations expects the driver shortage to grow to 239,000 by 2022. That dynamic will be much worse if regulatory pressures, such as the ELD mandate, encourage more drivers to leave trucking.