When are you allowed to cross a level crossing with flashing lights but no barriers after a train has passed?

Your answer is correct. At a railway crossing with flashing red lights and no barriers, you may only cross once the flashing red light has stopped. The red light signals that a train is approaching or the crossing is still unsafe. Even after a train has passed, another train might be coming, or the area may not yet be clear. Do not rely on other vehicles' actions; always wait for the red light to go out before proceeding. This rule helps to ensure your safety and prevents accidents at railway crossings.