Traffic Signal !!!!

Ok this incident is a freak in its own kind. 5-6 months back i would have never thought that I will travel in OMR (old mamallapuram road) often. But then you never know whats next in your future isn't it. I used to travel to the heart of the Chennai city namely Nungambakam...ofcourse my old office. Now for the past 6 months I am forced to travel through OMR, guess what yes my new office is now situated in OMR. Here comes the real part of this story, there's a traffic signal near Thiruvanmyur, although its not the main signal but it is some what crowded. So often when I come to this signal I see a bus in front of me 21D, imagine everyday I travel and if I am not wrong but 99.99% of time I stop at this signal because it says halt (red sign). and this bus 21D will be in front of me. I have never crossed this signal without stopping..I mean I have never escaped the red sign all these 6 months...you might be thinkking now that its a daily routine and there's a fixed time when cross this signal but to my knowledge I have gone through this signal on differernt timings. But may be there's soemthing between me and the bus 21D and without any doubt the mysterious traffic signal.