U.S. pipelines at a crossroads
The San Bruno explosion helped raise the total cost of U.S. pipeline accidents in 2010 to $980 million , more than triple the annual average from 1991 to 2009. And since the ruptured pipe was 56 years old, it also revived doubts about the safety of aging pipelines . More than 60 percent of all U.S. natural gas transmission lines were installed before 1970, according to the nonprofit Pipeline Safety Trust , and 37 percent are from the '50s or earlier. Around 4 percent — nearly 12,000 miles — are pre-1940, and some segments have been in place for 120 years. While pipelines have no official expiration date, age can amplify many other problems, PST executive director Carl Weimer tells MNN. "Certainly age is a factor," he says. "But with steel pipes, age isn't the main problem. It's more how it's constructed, maintained and operated."