So true Rob - Natural gas lines used to have external pressure sensing lines to detect upstream pressure changes and communicate to the gas regulator. These sensing lines were in the same trench just above the gas main. A few years back a backhoe operator was digging without locates and hit the sensing lines not knowing what they were for he kept digging. Unbeknownst to the ignorant backhoe operator the regulator station a km away sensed low pressure due to the leak on the sensing line and opened up wide and put over pressurized gas into the system blowing up about 200 homes. What a mess. A little checking (locates) and clearing with parties can really minimize damage.