If you want to trigger the traffic lights with 100% certainty, simply get off the bike and lay the front wheel of the cycle flat over the loop towards one corner for a second or two. The rim of a cycle wheel acts like a big short circuited turn of wire and used in this way will produce a bigger signal than most automobiles do. The reason for this is that you can place your wheel flat on the ground so that it is about 10 x closer to the loop than most automobiles can reach." -- Graham Lill, Dept. of Infrastructure, Energy, & Resources, Tasmania