private void addPlane_Click(object sender, EventArgs e)
        {
            addConveyance addConveyanceObj = new addConveyance("Plane");

            addConveyanceObj.ShowDialog();
        }
        private void addBusBtn_Click(object sender, EventArgs e)
        {
            addConveyance addConveyanceObj = new addConveyance("Bus");

            addConveyanceObj.ShowDialog();
        }