What lights are required for a barge, not part of a composite unit, being pushed ahead?

A barge that is being pushed ahead and is not part of a composite unit must display specific navigation lights according to the international and inland rules. When a barge is being pushed and not self-propelled, it is considered a vessel that must have its own identification and lighting.

The correct answer indicates that the barge must show sidelights and a special flashing light. Sidelights are crucial for indicating the port and starboard sides of the vessel to other navigation traffic, while the special flashing light serves as an additional warning and identification feature, signaling that the vessel is being pushed and its status on the water. This is essential for safe navigation, as other vessels need to be aware of the presence and direction of the barge. The special flashing light helps to further distinguish the barge, providing visibility especially in conditions of reduced visibility.

The other choices do not meet the requirements as dictated by the navigation rules for a towed or pushed barge. A sternlight alone, only sidelights, or a single white light do not provide the necessary separation of visibility and identification that is critical for ensuring safety in navigation. Thus, the combination of sidelights and a special flashing light is required to comply with navigational safety standards.