I overlook the M18. At 3.08am I was walking the (nocturnal) dog around the back yard when I heard a loud bang, like a shotgun. Looking in the direction of the motorway I saw a small cluster of orange lights moving swiftly along. There were another nine bangs with irregular timing, and my directional lugholes said that they emanated from the orange lights. After the lights had gone out of view the bangs stopped, which is odd because I can hear the motorway to the south of here even though I can't see it. I have no explanation for this phenomenon.
Bill