Originally Posted by
cyccommute
Sorry but there is no real good way to detect them after they have been buried. Position over the loops for a small conductive object like a bike is very critical.
I hate to reply to my own post but I have been noticing something on older paving that covers the pavement cuts. With traffic and time (lots of time, on the order of years), the pavement over the saw cuts will start to crack. I've been noticing the lone linear cracks appearing at several intersections but they are can be difficult to detect because they are subtle. There's no hope for fresh paving jobs.