Regents park in London has an inner circle over a hundred years old, it is a perfect circle approximately 1km in circumstance with uneven terrain and lots of trees.
I am sure many other cities have similar large perfect circular roads.
Eli5 How did they ‘draw’ the road on this scale before building it?
In: 0
I measured it on Google Maps and it does have a small difference on radius between the north-south and east-west axes, so it’s not totally perfect though the deviation is only a few meters, meaning less than 1% error. It’s nice but not that uncommon for prestigious construction projects.
There’s several ways to build it. You can extend objects of known length – such as ropes or wooden scaffolding – from the center to indicate where the desired edge of the circle would be.
You can use a theodolite.
You can observe the angle of your road in small sections and then sum those sections together.
Also I’d point out that the pavement isn’t over a hundred years old so it’s possible that when the pavement was laid, the circle was widened or corrected.
Latest Answers