So if you created an "airfield" object, you can add a runway by selecting the airfild object and pressing ctrl+b if I recall that correctly. Then you can customize the runway belonging to your airfield and your spawnpoint in length, wide, place and orientation. If you move your spawnarea on the runway, the runways signs, should actually be place along the side of your object "runway". Well, If not, how knows, there isn“t anything in this game and the FMB which surprised me at all...