"ORBIS is a multimodal, seasonally variable transportation network model available at orbis.stanford.edu. The model provides for practically unlimited permutations by allowing users to limit modes, change movement cost, and adjust time of year. However, it is as a more simple network that ORBIS can be usefully integrated into other research, such as historical environmental reconstruction or agent-based modeling set in the Roman world.

With that in mind, this view of the ORBIS network is provided as a simple node and edge list. Nodes are sites and include X and Y coordinates for geographic positioning. Edges have source and target (but no geometry) as well as distance in KM, cost in denarii per kilogram of grain delivered by wagon, and duration of travel in days of each route segment either based on calculated time (for sea routes), fixed speed (for rivers) or 30km/day speed (for roads). The type of the route is also included.

Note that to facilitate interoperability with network analysis packages that do not support parallel edges that in cases where ORBIS has parallel edges (where, for instance two sites may be connected by both a road and a river) that only the cheapest edge has been kept."

Text from: https://purl.stanford.edu/mn425tz9757