I can figure a string line, but if you are using a 500 foot string line and you are even off by 1/2, that will end up being in a completely different part of town or on someone’s property by the time you are done. Do they just guesstimate and then when they see they are coming off they make curves or adjustments in the road? I know most roads arn’t straight, but the process still fascinates me.
In: 90
Surveying tools. Take a spyglass and then put two targets as far as you can see with it and have them stand at a certain distance. Then from that one point you are standing take the angle of the other target from your perspective. Then walk to the other side of the road and take the measurement again.
You now have 2 triangles with which you can get all the dimensions and you can make square with cross distance to ensure you have it straight.
Although nowadays you have a dude with high precision gps receiver who places markers. Follow the markers with sufficient tolerance, check periodically and you will stay straight.
There GPS based marking tools are with in a millimeters. I have had a pleasure of working on a site where the positions of steel structures pillars were given us with this. There were studs on the concrete foundation. They were more accurate than our tape measures.
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