Thank you all for answering.I cheked with traffic department, what they told me is that I have driven my car in the service road (Near Airport after Pak Sama signal right side small roads, when coming from Doha to Mesaied).Actually I did not know this is traffic violation,Although I see every day thousnad cars are driving in that road,specially in the morning.However I stopped driving there,because I don't want to pay QR 500 again.