Maps of Roman roads are common in the study of antiquity. What identifies a route as Roman, however, is often less certain than such maps suggest. In the case of the wheel-rut roads (Geleisstraßen) in the Alps, for example, Swiss research on historical roads has shown that visible rut marks are frequently medieval or modern, and that the attribution “Roman” often rests solely on measurements that cannot be securely dated.

The project takes these forms of evidence as its starting point. New results from heritage authorities, historical societies and excavation firms are collected and related to terrain models derived from laser-scan data, aerial imagery and historical maps. In each case the question is what a single observation can actually support. An excavated road, a hollow way, a milestone, a bridge, a field name and a line on an old map each allow different conclusions about a route.

Road infrastructure. Beyond the road itself, the infrastructure belonging to a route comes into view. This includes bridges and fords, milestones and settlements. Funerary sites hold a special place: in Roman times they frequently lay along the arterial roads leading out of settlements and are therefore regarded as indicators of a nearby route.

Waterways. A transport network does not consist of roads alone. Alongside the seas, rivers formed the backbone of the movement of goods, and only a combined view of both systems allows reliable statements about it. Their courses have changed considerably since antiquity, and former channels and small streams have in part disappeared entirely. Historical maps such as the Urpositionsblätter and the Bavarian Urkataster show the watercourses before the river regulation of the nineteenth century and are thus the starting point for reconstructing earlier courses.