Surveyed alignments and agger earthworks become standard

By the late Republic, Rome had learned a hard truth: speed on campaign began with the ground. Surveyors—agrimensores with gromae and measuring rods—drew lines across maps and hillsides that ignored meanders. Strabo’s praise captured the result: roads ran where they needed to, with cuts through hills and embankments across valleys, robust enough that wagons could carry “boat‑loads” [2].

The agger, an elevated embankment, became the signature earthwork. Built of compacted fill and faced where necessary, it lifted the roadway above seasonal water and created a profile that shed rain. At Aricia south of Rome, the agger carries the Appia across low ground; near Narbo in Gaul, the Domitia rides a straked bank above the Rhône’s reach; in Macedonia, the Egnatia’s embankments negotiate passes and marshes that otherwise swallowed wheels [2][10][17].

Geometry complemented earth. Straight alignments minimized distance and forced consistent gradients. Where hills rose, surveyors cut benches into tufa and limestone; where valleys fell away, they threw up aggers and built culverts. The surface, per Vitruvius, was layered—rudus, nucleus, and the hard summum dorsum—then crowned in a camber. The sound that resulted was a confident clatter over stone, not a splash through mud. Bronze measuring points, scarlet surveyor cords, and chalk marks on rock turned landscape into a plan [4][20].

The approach generalized quickly. In Britain, military roads struck straight across the midlands; in Hispania, stretches approached bridges like the Roman crossing at Alcántara in ruler‑true lines; in Italy’s Pontine Marshes, causeways ran so that Horace could joke about taking one’s time on the Appia while still trusting the ground to carry him [5][13][17]. The Antonine Itinerary’s station lists presuppose such consistency: a mutatio every 8–12 Roman miles, a mansio at the day’s end.

Even drawings got standardized. The schematic tradition preserved in the Tabula Peutingeriana is not a landscape painter’s work, but it truthfully conveys what mattered: connectivity by segments and nodes. The embankments and straight lines that Roman surveyors drew were translatable into that diagram—Rome’s world as a network of corridors, not a set of scenic detours [7][16].