It is difficult to draw a standard for this kind of drawing without computer drawing. I summarized the manual drawing:
1 Draw two groups of rectangular lines consisting of two squares first.
Cut a square diagonally in each group of rectangles to draw the first three-eighth circle, and the same is true for the other group, with the circles in opposite directions.
Then the two groups of cut rectangles are butted together and glued on a piece of paper, and a relatively standard S-road can be drawn.
The drawing scale can be 1: 100.