CHARLESTON, W.Va. -- Nearly 15,000 miles of natural gas pipelines are spread across West Virginia, enough to stretch from Charleston to Morgantown and back 50 times.
Such pipelines are considered by many experts as the best way to transport fuel, much safer than railroads or tanker trucks.
But serious dangers remain, as West Virginians were reminded Tuesday with scenes of a wall of fire above Interstate 77 from the huge gas-line explosion in Sissonville.
And despite numerous efforts at reform, recent investigations and audit reports show that many gaps remain in the oversight of the nearly 2.5 million miles of pipelines that crisscross the United States.
Nationwide, concerns about pipeline safety have grown, amid a boom in natural gas drilling in several states and in the wake of a string of serious accidents, including explosions in San Bruno, Calif., and Allentown, Pa., that killed a combined 13 people in 2010 and 2011.
"While many stakeholders agree that federal pipeline safety programs have been on the right track, the spate of recent pipeline incidents suggests there continues to be significant room for improvement," the Congressional Research Service concluded earlier this year.
In a March report, for example, the U.S. Government Accountability Office warned that many so-called "gathering" pipelines, which transport gas to processing facilities, escape federal scrutiny altogether.
Preliminary reports indicate that Tuesday's Kanawha County explosion occurred on a 20-inch-diameter transmission line near Columbia Gas Transmission's Lanham Compressor Station at Rocky Fork. That would put the pipe involved on the smaller end of the spectrum for gas transmission lines, one of the myriad types of pipelines that send gas from where it is produced to where it is used.
Gas companies use "gathering" lines to transport natural gas from well sites to compressor and other processing facilities. From there, transmission lines -- usually ranging from 20 to 42 inches in diameter -- carry gas across long distances from producing regions to local distribution companies.
From those companies, natural gas is piped through distribution lines or "mains" -- which range from 2 inches to more than 24 inches in diameter -- to homes and businesses.
In an analysis earlier this year, the conservative Manhattan Institute compared accident, leak, injury and fatality rates among various modes of transportation for oil and natural gas. They found, for example, that natural gas pipelines recorded less than one accident per billion-ton-mile of material transported. That compares to 650 incidents for highway transport and 20 for railways.
"The evidence is clear," the group said, "transporting oil and natural gas by pipeline is safe and environmentally friendly. Furthermore, pipeline transportation is safer than transportation by road, rail, or barge, as measured by incidents, injuries and fatalities - even though more road and rail incidents go unreported."
Still, in the last five years, pipeline accidents across the country have claimed the lives of 21 workers and 47 members of the public, according to data from the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration, or PHMSA.