Romans Had Paved Roads?

[Jinx]

Recently, I read that the Romans had paved streets, or pretty close. They used large stones with the gaps filled in by smaller stones, etc. But, how did they get the stones flat? I WAG a chariot could have dragged a roller behind it to press the stones flat? - Jinx

[Shagnasty]

How is this different than say Colonial America? Boston still has some roads and alleys just like that from that period and they didn’t have much that the Romans didn’t have. I don’t know much about stone building techniques but I think they just looked for rocks that were flat on one side and dug the rest into the ground. If there a ton of rocks around it doesn’t take much find ones that are pretty flat already.

[Walloon]

The Construction and Makeup of Roman Roads, by Adam Pawluk.

[DrDeth]

Their roads were not nessesarily made for wheeled vehicles, although such could be used on them. They were made for Roman legionaires to march on, swiftly.

[Philster]

Yeah if they needed to quickly take some to flank the attackers…eh, um…oh nevermind.
I flunked flank.

[Giles]

Apart from many stones being found naturally pretty flat, you can flatten them the same way as you flatten stones used for buildings: chisel away the bumpy bits.

[CJJ]

@Walloon

The Construction and Makeup of Roman Roads, by Adam Pawluk.

Thanks for the link Walloon; I very interested in Classical civilization and have been to Italy more than once, but never really gave the construction of Roman roads much thought.

A key point in the linked article is that paving stones are relatively rare (compared to the length of the road); the top layer was often a metallized gravel, some of which was gathered from the soil excavated for the side draining ditches (those Romans were very efficient). Limestone–a sedimentary rock which is easily cleaved to produce flat surfaces–was used for flagstones to support the gravel.

Incidentally, if you ever visit the Roman forum, you will see the Via Sacra, which in many stretches is a terribly unstable surface. When I saw it, I wondered how any Roman would find this a suitable road for the heavy commerce of the Forum, but then I learn the road had been mistakenly excavated when Napoleon arrived in Rome and began exploring the forum. His army tried to put the road back the way they’d found it, with (at best) mixed results.

[ralph124c]

I recall that the best Roman roads (like the Via Appia) were often as deep as they were wide. With such solid contruction, they lasted 2000 years. anybody know how much they cost to build (per mile)? it would be interesting to know how much wealth was expended on road building.

[Kimstu]

@CJJ

A key point in the linked article is that paving stones are relatively rare (compared to the length of the road); the top layer was often a metallized gravel, some of which was gathered from the soil excavated for the side draining ditches (those Romans were very efficient).

“Metallized gravel” is kind of misleading. As discussed in a recent thread, terms like “metalled road” and “road metal” just refer to road surfacing in general, and usually don’t imply the use of substances now known as metals. Non-metallic gravel, pebbles, stones, etc., qualify as “road metal” all by themselves. And that’s the sense in which the linked article refers to them as quarried from drainage ditches:

Roman roads are characterized by various ditches, the different types of which served multiple functions. One type of ditch is really a sort of quarry, not only draining the water from the road surface, but providing gravel and material for remetalling directly along the route.

However, the article also mentions occasional use of ore slag from iron mining as a surfacing material: a rare instance of “road metal” actually being the stuff that we call metal!

“In districts where iron was being worked, the hard slag [the waste metal created in producing iron] provided an almost ideal metalling, which seems in some cases to have increased its effectiveness by rusting together into an uncommonly hard concrete-like mass” (21). Chevallier confirms this with a citation from the work of the classicist Broise which says that some roads used iron slag, as a binding and sort of pavement. Some other roads were metalled with a sort of rough concrete; a combination of gravel bound with a little mortar.

[CynicalGabe]

REG
All right, Stan. Don’t labour the point. And what have they ever given
us IN RETURN? (he pauses smugly)
XERXES
The aqueduct?
REG
What?
XERXES
The aqueduct.
REG
Oh yeah, yeah they gave us that. Yeah. That’s true.
MASKED COMMANDO
And the sanitation!
STAN
Oh yes … sanitation, Reg, you remember what the city used to be like.
REG
All right, I’ll grant you that the aqueduct and the sanitation are two
things that the Romans HAVE done …
MATTHIAS
And the roads …
REG
(sharply) Well YES OBVIOUSLY the roads … the roads go without saying.
But apart from the aqueduct, the sanitation and the roads …
ANOTHER MASKED COMMANDO
Irrigation …
OTHER MASKED VOICES
Medicine … Education … Health
REG
Yes … all right, fair enough …
COMMANDO NEARER THE FRONT
And the wine …
GENERAL
Oh yes! True!
FRANCIS
Yeah. That’s something we’d really miss if the Romans left, Reg.
MASKED COMMANDO AT BACK
Public baths!
STAN
AND it’s safe to walk in the streets at night now.
FRANCIS
Yes, they certainly know how to keep order …
(general nodding)
… let’s face it, they’re the only ones who could in a place like this.
(more general murmurs of agreement)
REG
All right … all right … but apart from better sanitation and medicine
and education and irrigation and public health and roads and a freshwater
system and baths and public order … what HAVE the Romans done for US?
XERXES
Brought peace!
REG
(very angry, he’s not having a good meeting at all)
What!? Oh … (scornfully) Peace, yes … shut up!

[Chronos]

Apart from many stones being found naturally pretty flat, you can flatten them the same way as you flatten stones used for buildings: chisel away the bumpy bits.

You can also get a couple of stones very flat by rubbing them against each other in an irregular pattern. Sure, it’s a lot of work, but then, so is just getting them to whereever you’re going to put them in the first place.

[CJJ]

@Kimstu

“Metallized gravel” is kind of misleading…terms like “metalled road” and “road metal” just refer to road surfacing in general, and usually don’t imply the use of substances now known as metals. Non-metallic gravel, pebbles, stones, etc., qualify as “road metal” all by themselves…However, the article also mentions occasional use of ore slag from iron mining as a surfacing material: a rare instance of “road metal” actually being the stuff that we call metal!

Thx for the correction Kimstu. “Metalled gravel” is just gravel, I jumped to a conclusion based on the later mention of ore slag in the article. Chalk one up for fighting ignorance:)

[Helen_s_Eidolon]

@DrDeth

Their roads were not nessesarily made for wheeled vehicles, although such could be used on them. They were made for Roman legionaires to march on, swiftly.

Well, yes, they were intended to transport armies - which included all the baggage wagons. So wheeled vehicles were one of the primary concerns.

[sweeteviljesus]

@Chronos

You can also get a couple of stones very flat by rubbing them against each other in an irregular pattern. Sure, it’s a lot of work, but then, so is just getting them to whereever you’re going to put them in the first place.

And you can get three stones dead flat by rubbing A against B, B against C, and C against A. Not that this has anything to do with road building, but I think it is one of the coolest applications of applied geometry ever.

[Walloon]

Merriam-Webster defines road metal: broken stone or cinders used in making and repairing roads or ballasting railroads

[garygnu]

The Romans had concerte, too. Was it used in road construction?

[Captain_Amazing]

@CynicalGabe

REG
All right, Stan. Don’t labour the point. And what have they ever given
us IN RETURN? (he pauses smugly)

You know, that debate in the Life of Brian actually comes from the Talmud, sort of.

Rabbi Yehuda, Rabbi Yossi and Rabbi Shimon were sitting and Yehuda ben Gerim was with them. Rabbi Yehuda said “How good are the actions of this nation (the Romans). They build markets, bridges and bathhouses.” Rabbi Yossi was silent. Rabbi Shimon responded “All that they established was for their own purposes. They built markets as a place for prostitutes, built bathhouses for personal enjoyment and built bridges in order to collect taxes.” Yehuda ben Gerim repeated this conversation and word reached the (Roman) authorities. They said Yehuda who praised will be rewarded, Yossi who was silent will be exiled to Zippori and Shimon who criticized must die.

[Tapioca_Dextrin]

@garygnu

The Romans had concerte, too. Was it used in road construction?

Don’t know about that, but Babylonians paved some of their roads with asphalt. You see a picture of one here.

[Can_Handle_the_Truth]

@sweeteviljesus

And you can get three stones dead flat by rubbing A against B, B against C, and C against A. Not that this has anything to do with road building, but I think it is one of the coolest applications of applied geometry ever.

This is true. A tool-and-die maker can make three hard steel plates flat within .001" (.025mm), using just a chisel, with the Three Plate Technique.