Which maintenance outcome primarily prevents Roman roads ('viae') from subsurface weakening when seasonal freezing occurs?

💡 Explanation

When water penetrates road layers and freezes, cryostatic pressure occurs causing heaving because ice expands, weakening the structure from below. Therefore maintaining surface camber for drainage minimizes water penetration and subsequent freeze-thaw damage, rather than annually replacing the statumen, applying sealant, or widening the agger, which address different issues.

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