How long would it take to build 30 miles of Roman road?

Say there's a route of 30 miles length in need of a road. Assume ready availability of stone and lime and possibly other materials. Some gentle slopes, no particularly adverse terrain or flora/fauna.

How long would it take for a team of road builders to complete construction, approximating Roman empire standard, assuming Roman empire technology? And how big would that team typically be?

• I'm not sure that any 'typical' value would be especially meaningful. The roads across the empire would have been built at different times in differing circumstances for differing purposes. Commented Oct 15, 2019 at 11:36
• Caesar's 50,000 or so legionnaires at Alesia built 25 miles of palisade wall about 10-12 feet high fronted by a ditch 8 ft deep in between 30 and 40 days. A legion camped every night in a fully fortified camp. Commented Oct 15, 2019 at 11:50
• Thanks for the edit Commented Oct 15, 2019 at 14:27
• FYI - while this question is clearly fine here, if you happen to be asking this because you're writing a fictional story, another site you could consider for questions like this is Worldbuilding.
– Joe
Commented Oct 15, 2019 at 21:03
• Thanks @joe .. they sent me here (because I was looking for more historically based reasoning) :-) Commented Oct 16, 2019 at 4:08

Tough to narrow this down, but at least a couple sources make what may be a useful comparison to more recent construction of Scottish military roads in the 1700s.

Direct comparison is obviously difficult, not least because there would inevitably be special circumstances surrounding the construction of roads in highland terrain, but it can at least provide some hints at what would have been possible in the Roman period. The expected rate of construction was 1 1/2 yards (1.35m) per man per day (at 16ft - 4.8m- most roads were just over 5 yards wide), and in at least one case 2 yards per man per day was achieved.

A second source , The Planning of Roman Roads and Walls in Northern Britain By John Poulter, references the same Scottish constructions as a proxy, and gives some numbers on the crew sizes:

So the bottom line figures out to 1 1/2 yards (1.35m) to 2 yds per man per day, assuming a typical 16ft wide Roman style road.

Note the last figure speaks of building a road 28 miles long in a single work season, which the book mentions was April to October. Reasonably close to your requested 30 mile road.

• For a basis of comparison - at est have a comparison of these roads to Roman roads that have lased upwards of 2,000 years. To the best of my knowledge, nobody before or since has made anything remotely comparable to Roman roads. One of the distinctions is the extreme depth of the Roman road-bed: feet deeper than anyone else's. Commented Oct 15, 2019 at 13:48
• Yes, its frustrating, I have done this research in the past, and can't find my notes. But the above authors, at least, are making this comparison.Still working on the Roman legion aspect... Commented Oct 15, 2019 at 13:57
• This article appears well researched. "The roadbed, six to nine feet deep, consisted of a layer of large stones, above which were placed smaller stones and debris mixed with lime, topped by flagstones held together with mortar." Where I live roads barely last 20 years - never mind 2,000. Commented Oct 15, 2019 at 14:19
• @PieterGeerkens Thanks, That did it, brought up one of the sources I had read before, The Roads of the Romans By .. Staccioli, Romolo Augusto Staccioli. Commented Oct 15, 2019 at 14:50
• @PieterGeerkens: survivorship bias, all the crappy roads the Romans built have long crumbled away and been replaced and forgotten. We'll have to wait 2,000 more years to see what stuff we've built will last until then. Also, Roman roads didn't need to support 80,000 pound vehicles traveling a mile a minute. That will put some serious wear on any road. Commented Oct 15, 2019 at 21:44

I don't know if this helps: but the Via Appia between Rome and Capua was built in 4 years (312 - 308 BC) The distance is disputed but was more than 100 miles. See EngineeringRome.org