try using this version instead:
if (isServer) then
{
_vehicle_87 = objNull;
if (true) then
{
_this = createVehicle ["Land_HBarrier_large", [11830.977, 12592.087, -1.5258789e-005], [], 0, "CAN_COLLIDE"];
_vehicle_87 = _this;
_this setDir 30.962219;
_this setPos [11830.977, 12592.087...