How the Romans Built Straight Roads.

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Welcome to this weeks offering. So have you ever wondered how the Romans built such straight roads. Me too. I probably think about it too much. So much so that I decided to make my own.

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Usual notices:
1. We are not historians or Academics. We enjoy researching and learning, and with that we enjoy sharing our journeys with you. That said, sources for information often listed below with credits.
2. Corrections. Whilst we make every attempt to not include any errors, research, and piecing stories together from dozens of sources sometimes leads to one or two. I will note here if any are found:

Errors
1.

Credit and thanks for assets

Filter: Snowman Digital and Beachfront
B-Roll Maps: Google Maps and Google Earth Studio
Maps: National Library of Scotland Maps:
OS Maps. Media License.
Stock Footage: Storyblocks
Music: Storyblocks, epidemicsound and artlist

Credit for images:

Triangulation diagram: Kasper Scott

Sources:

[pwhitewick]

Use Promo Code: "Whitewick10" to receieve 10% discount.

[disgruntledwookie]

Speaking as a math nerd, I can confidently tell you that even in Roman times they would have known quite well how to calculate the line direction from all those starting triangles. A bit of a tedious calculation perhaps, especially back then when they were relying less on sine/cosine and more on known geometric rules, but still a simple matter at the end of the day. Even just by drawing a scaled down version on paper with accurate angles and lengths, you could easily measure the final angle directly from the paper.

[LalaDepala_]

As a millenial who really misses 2000s/2005s "infotainment" television, your channel is very welcome in my life.

[joehopfield]

In 4th grade I was supposed to survey our school grounds (length and angles of perimeter).I used a spool of string, which got so tangled it took us a whole afternoon to untangle and measure... I hope you had as much fun as we did - a timeless challenge.

[adrianandrews]

That was very interesting. I have been studying this and similar topics for some 15 years and I think you will be interested in how I do what you have just done. I'm sorry if its a bit long !

What you need to do is create a map where angular relationships always hold BUT DISTANCES DO NOT. This is the opposite of modern maps where distances always scale but angles do not add up. This is because of the curvature of the earth, and yes it does matter even for distances as short as ten miles. You only need to measure the angles accurately - Roman kit could easily achive 0.25 degrees ( or 15 minutes ) of arc. It is never necessary to measure any distance on the ground or on the map - so no runners !

At the start, end and at each intermediate point erect a flagpole as an accurate sighting target. Look for a suitable target for the other end of your basline approximately perpendicular to the direction of your target and as far away as possible. Pick a second target at about 135 degrees and a third at about 20 degrees from the start w.r.t. the baseline. When all four flags are in place point the Zero along the baseline and measure the four angles from the baseline accurately. Now draw a basline on paper at the bottom and with ends about 1/3 and 2/3 the width of the paper. Draw the four lines corresponding to the four angles. Where they cross gives the second and third targets on your map. The line between them is your Second Baseline.

If luck is with you the endpoint will be visible from the ends of the second baseline. [ If not repeat the first process again until it is the case ] . Measure the angle of the endpoint from the end of the second baseline. Transfer this to your paper map. Where the lines cross is the endpoint, Finally draw a line between the endpoint and the start point. The angle to the baseline is the bearing to start the build.

You can verify your surveying using Google Earth. Draw a Great Circle arc (not a straight line ) from the start to the end and note the bearing of the line. Do the same from the start to the first target. The difference between them corresponds to your measurement. In my case, in the hilly regions of southern France I invariably got within a degree of the true bearing.

[pras]

I recognised the dioptra from other drawings I have seen, but I have always seen it with a device or devices to help ensure the top surface is horizontal (in 3D) when a bearing is taken.
Sometimes these devices take the form of plumb bobs hanging from several points on the periphery of the circle. A mobile dioptra would have a sharp point to stick in the ground. It could then be determined (by eye) that each of the bobs was parallel with the central shaft. This way you could make the dioptra level even if the ground was not.
Maybe you levelled it using another method (possibly using a phone app or a spirit level) but I did not see it in the video.
For anyone wondering, levelling your dioptra improves the accuracy of the readings you take.
Just a thought,
Patrick

[riderramblings]

A fascinating episode and, finally, after years of _Promos_ on a multitude of channels you, of all people, show one I am actually interested in.

[frenchfriar]

It seems fairly obvious that most Roman roads were surveyed in a similar manner, and built from both ends to meet in the middle, which allows for some of the slight bends we see that don't appear to have any particular reason for being there.

Add to that that the Romans would have surveyed with teams, possibly large ones, to have the manpower to run measures and sight angles, it's really not as hard as it sounds to get roads that stay straight over very long distances.

But even so, it pays to remember that those roads were not perfectly straight, they do have slight bends in them occasionally.

Often, those aren't even perceptible until you map them.

But having good sight lines made a world of difference.

[MarkThomasMedia]

Keep them coming. Such a great diversion from the sea of troubles in the world today!

[WCUKProductionsLtd]

I take my hat off to you for this, Paul. First off, there’s no way I could have built that thing and then secondly, there’s no way I couid apply anything I learnt in maths at school. It’s all gone from my brain - decades ago!

The fog would have been the final straw.

This is citizen science in action. Great stuff!

[bauerwesterentarot]

8:39 "This is what makes me feel alive." What a wonderful thing to realize about yourself!

[NicholasproclaimerofMessiah]

That works. That gave me the gist of how they did it, and I had no idea before.

[Jimyjames]

Hello Paul 😄 Yeah @ 0:47 "A Spectacular View" - yeah a 'A Spectacular View' of Mist & Fog!!! lol 😄😄 Well done for trying - hope you didn't hurt yourself too much when you slipped - Take care 🙂🚂🚂🚂

[cthompson]

As a kid I would help my dad perform surveys with a theodolite. My job was to walk out with the big measuting stick so he could determine the lay of the land. Your contraption seems much lighter. :)

[thetessellater]

This is the same procedure that Ordnance Survey used to accurately map Britain, using 'Trig Points' upon which they mounted theodolites. These points, also called 'Triangulation Stations' were square concrete pillars, one of which I remember stood on top of the hill upon which Central Milton Keynes shopping centre was built in the later '70s ( They scraped the hill top flat for the long building, and made a 'viewpoint' or belvedere with ithe spoil. )

[chrish]

Amazing, practical archaeology visualised. Well done. If you did it again what would you do differently?

[tomlee]

Maths was never my strong point and I never understood sines and cosines etc. However, I found this fascinating and admire the lengths you go to, to keep us enthralled. Thank you.

[smallsleepyrascalcat]

Pretty impressive for some wood! Very enjoyable video. The Romans surprise me in every video it seems.

[andymcgeechan]

Mesolithic man would use two sticks (with a helper) and lay perfectly straight lines over hundreds of miles. The end destination - let's say Great Langdale - would already be the target so a bearing would still be needed to be maintained from the start point - say Mount Ventoux. The people with such skills would be from the areas where cave painting reached it's zenith 20.000 years ago. Tying in with a previous video of yours, Cornwall to Doggerland (Silver Pit Lake) is traceable by place names to this day. Perhaps I could animate this hypothesis in a visit to your studios facilities.

[imdiyu]

The title made me click on this video. But, your excitement was what that made me watch till the end.

And the most poignant part of the video (in my opinion) was when you said, "2000 years ago perhaps there was someone else struggling with the same problems." I relate to such things, I have felt that quite a few times too. And it filled me with awe and wonder, just as your video did.

Thank you so much 😇