Traffic on U.S. roads is growing at the fastest rate in almost two decades, as cheap gasoline, coupled with a strong economy, encourages motorists to use their cars more. U.S. motorists drove 3.12 trillion miles in the 12 months ending in September 2015, an increase of 3.4 percent from the same period ending September 2014. The increase was the fastest since 1997 according to data compiled by the Federal Highway Administration ( tmsnrt.rs/1QHEiNh ). The driving boom shows no sign of fading. Traffic volume was up 3.4 percent in September compared with the same month a year earlier after seasonal adjustments. Cumulative traffic volume in the first nine months of 2015 is 3.5 percent higher than in the same period of 2014 […]