A road segment is one record in the Itiner-e dataset: a single line between two places or junctions, with its own length, type and certainty. A named road such as Watling Street is made of many segments joined end to end.
Key takeaways
- Our map holds 14,769 segments, and tapping a line shows the one segment you touched.
- A segment is cut where another road crosses it, so one named road is split into many pieces.
- Each segment has its own certainty and type, so a single road can change from conjectured to hypothetical along its length.
- Only 39 roads carry a name in the data, so most segments are unnamed.
How a road segment works
Itiner-e does not store roads as long unbroken lines. It stores segments. Each record is a stretch of road running from one point to the next, and it carries its own set of fields: an identifier, a name, a type (main or secondary), a certainty class, the sources it came from, its length and its average slope [1].
The name of each record is built from the two ends of the segment. The atlas uses the ancient place name where it is known and the modern name where it is not, joined by a hyphen. If a road ends where there is no settlement, a landmark is used instead [1].
Segments end at junctions. The paper explains that a single named road, giving the example Rome to Capua, is split into several segments where other roads cross it, or between a starting point and the nearest intersection. Those segments share a name, type and author, but each keeps its own length and slope [1]. They can also differ in certainty, because the evidence for one stretch may be much better than for the next.
Segments also let the atlas record where a road was joined up from different studies. In Britain, for example, the paper notes that some road sections were connected with straight lines to make an interconnected network [1]. So a line on the map is a modelled stretch, not a record of a surviving surface.
An example from our data
The whole map is made of 14,769 segments with a combined length of 299,171 km. Of those, 1,040 are certain, 12,952 are conjectured and 777 are hypothetical.
Watling Street is 352 km long and made up of 58 segments. Ermine Street is 421 km in 68 segments. The Via Flaminia is 307 km but only 6 segments, so the number of pieces depends on how the road was cut in the data, not on its length alone.
When you tap a line, the panel describes that segment alone. To see a whole road at once, use its road page.
The thing people get wrong
A segment is not a "road" in the everyday sense, and a segment count is not a count of roads. The data holds 14,769 segments, but only 39 roads carry a name, covering 4.2% of the length. Most segments are unnamed local links, and many belong to larger routes that the sources never named. If you want to know how many separate Roman roads existed, the segment total will not tell you.
Frequently asked questions
How many segments are on the map?
14,769, covering 299,171 km across 39 countries.
Why does one road have so many segments?
Because a segment ends wherever another road meets it, and where the sources change. A long road with many junctions is cut into many records.
Are segments the same as Roman road sections you can visit?
No. A segment is a unit of data. It can be a few hundred metres or many kilometres, and it does not follow the edges of any surviving remains.
Sources
- Itiner-e: A high-resolution dataset of roads of the Roman Empire, Scientific Data (Brughmans et al., 2025).
- Itiner-e dataset (version 2024 1.3), Zenodo.
- Every figure from our own map is worked out from the datasets on the data sources page (checked against Itiner-e version 2024 1.3).