I have had Trapster on my phone for several years. A friend told me about it since she commuted to work 100 miles a day.
I tried it back then and it really worked. Since that time it has improved and I now have it on my new phone. It will alert you and let you know about those radar traps. Because the traps are everywhere in our town, it is a little aggravating to get al the notices. But since I don't usually speed, I can't say it has saved me a ticket. But my husband on the other hand, has a heavy foot and it is a must for him. He can't stand getting any more points on his license. Try it and see.