You can't add on safety. It has to be designed that way from the start. For example, on airplanes it's safer to have the wings below the cockpit because it give

You can't add on safety. It has to be designed that way from the start. For example, on airplanes it's safer to have the wings below the cockpit because it gives the pilot more visibility. If you weren't thinking about that when you designed the plane you would be hard-pressed to make that change.