The road to U.S. energy security is often unpaved. In southern Texas and North Dakota , where shale drilling has propelled U.S. oil production to the highest level in 28 years, thousands of 18-wheel trucks are rumbling to wells on roads designed decades ago for farmers to bring crops to markets. Road closures have slowed output, with diverted traffic increasing accidents, as Texas seeks $1 billion to maintain roads in the oil belt. With the U.S. projected to be energy self-sufficient by 2030, according to BP Plc (BP/) , crumbling highways may threaten billions of dollars of investment in the oil patch. Because more wells are being drilled using hydraulic fracturing, there’s greater need for truckloads of water, sand and chemicals, as well as steel structures used in the process in fields often miles from major roads. “If you drive a cattle truck one or two times a year, […]