What defines a Major Aid in terms of ATON structures?

A Major Aid to Navigation (ATON) is characterized by its significant design and construction, which typically involves substantial engineering and resource allocation. The correct answer highlights that the design of significant ATON structures is managed by Civil Engineering Units (CEUs). These units are responsible for ensuring that the aids are robust and reliable, suitable for navigational needs of broader maritime traffic and capable of withstanding environmental challenges.

Major Aids are typically more complex than simpler navigation markers, requiring thoughtful design and adherence to safety and operational standards. They serve critical roles in facilitating safe passage for vessels, marking navigable channels, and ensuring hazard warnings. The involvement of CEUs signifies the importance of these structures and the expertise necessary in their conception and implementation.

In contrast, other choices relate to characteristics or aspects of ATON structures that do not capture the essence of what defines a Major Aid. Minimal maintenance or being simple navigation markers does not reflect the complexity and operational significance associated with Major Aids, while single pile structures, although they may serve a navigational purpose, do not necessarily denote the level of engineering and design considerations typical of Major Aids.