This phenomenon has not been studied properly and has not been experimentally verified.
There is an article on the phenomenon in wikipedia here:
Street light interference - Wikipedia, the free encyclopedia
I'm very interested in it.
It might be worth your while to contact a physics professor at a local university. They may be able to point you to someone who would be well trained and interested in helping you to investigate the phenomenon. At the very least, someone would be able to document proper scientific experiments carried out with you to put some scientific study in the area out there; something which is lacking at the moment.
Please, if you do decide to do something along these lines, make sure to let us know if a paper is published :). Some experimental verification of the phenomenon would be very useful.