I have done some further analysis on the two lines That I measured throughout a day. I measured the movement of the two E-W alignments where they are within 30 m of each other down my street. To my utter amazement, the two lines move virtually in synch with each other! As you can see below in my hand drawn and rough graphs, the difference is negligible.
Looking at the classification of lines by Rory Duff, these are Type 3 sound lines. According to him, I am not picking up what should be a whole bunch of other lines of different types but for now, I’d rather not. I’d like to complete mapping these lines through the city and see if there are others. Then and only then, shall I look for other lines…..