How do they decide the way mountain roads twist and turn?
In: 200
The short answer is that they follow the landscape. In flat areas you can simply build a road relatively straight from your origin to destination, with a few gentle curves going around obstacles. In steep mountains, going in a straight line would mean going straight up and down cliffs and steep slopes. However heavy trucks can only go up a relatively gentle slope of 10% or 1 in 10. If you have lots of resources, you can build bridges over the canyons, and tunnels through the mountains so that the road is nice and straight. However the cheapest place to build a road is on the existing ground surface, following all the little ridges and gullies. A road going through a gorge will have to follow the twists and turns lf the gorge.
[This map](https://www.topomap.co.nz/NZTopoMap?v=2&ll=-41.029361,172.930947&z=14) shows a twisting mountain road. It also shows the contour lines of the landscape and you can see that they are very similar. This road is following all the little ridges and valleys. [This road](https://www.topomap.co.nz/NZTopoMap?v=2&ll=-44.818691,168.108161&z=14) is also following the contour lines, but since there are less ridges and gullies, it has less curves.
Here is an example of where bridges, tunnels, and cuts into the hillside have been used to make the road straighter. [SH1](https://www.topomap.co.nz/NZTopoMap?v=2&ll=-36.555132,174.678681&z=14)
Latest Answers