Northern California residents shouldn’t necessarily be alarmed over the next couple of weeks if they see a blue SUV with weird-looking sensors sticking out of it cruising around in the wee hours of the morning. It’s just PG&E’s natural gas detector, which is traveling throughout the utility’s network using extremely sensitive instruments to find gas leaks. The surveys are done mostly between 1AM and 6AM because that’s when the atmospheric conditions allow the sensors to work best. If a leak is detected a repair crew gets to work on it right away. This year the leak detection truck will drive more than 31,000 miles of gas distribution line. This week and next it’ll be Chico, Willows and Redding. PG&E has taken a number of corrective actions on their gas network since the disastrous San Bruno explosion. They recently installed a series of inspection safety valves in the North Valley, and they’ve eliminated all 800 miles of cast iron pipe. When people see PG&E repair crews at work, there’s likely to be a smell of gas.