How Safe Are America's Natural-Gas Pipelines?

After last week's devastating explosion in the San Francisco suburb of San Bruno killed at least four people, two mayors in New Jersey opposed natural-gas projects in their cities. But the 30-inch pipe in San Bruno was laid underground more than 50 years ago, before the 37 homes destroyed last week were even constructed. How many more such disasters are waiting to happen elsewhere in the country? Are too many pipes too old? How often are they inspected? Should homeowners be told about big distribution lines near them? We talk with public utilities, former regulators and independent watchdogs.