--- a/roadveh_cmd.c	Thu Jan 27 20:38:19 2005 +0000
+++ b/roadveh_cmd.c	Thu Jan 27 21:00:05 2005 +0000
@@ -115,6 +115,8 @@
 	uint tile = TILE_FROM_XY(x,y);
 	Engine *e;
 
+	if (!(IsEngineBuildable(p1, VEH_Road))) return CMD_ERROR;
+
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);
 
 	cost = EstimateRoadVehCost(p1);