For many years, increased regulation and tougher industry requirements were credited with playing a significant role in reducing the number and severity of truck accidents; by 2009, the mortality figures were less than half of what they’d been 30 years earlier. But several factors may have played a part in the subsequent increase in fatal crashes, including more trucks on the road, driving millions of more miles each year. Today’s big rigs have more built-in safety features than ever before, but driver shortages, aging fleets, inadequate training and other industry woes have contributed to the problem.