Here is Bret Devereaux's description:

[...] a large international research team has just unveiled itiner-e, an amazing new project that mapped not only major Roman roadways, but minor ones as well. This is a really great project – most maps of the Roman road network only include the really major arterial roadways, but of course we’ve long known about many smaller. Even better, they’ve released a handy, easy to use map model of their research which you can use online, where you can click on any road segment and get a neat summary of what we have about it – if the location is secure or conjectured, if it has a name, what sources we have for it, etc. Visualizing not just the presence of roads but the density of them in certain areas really does help remind us that Roman power (and population) was not uniformly dense.