So I've got a bezier curve and I want to use it to create a super simple road. The road object is literally just a plane. Whenever I add the array modifier to the road and set it to fit curve it only extended twice the length it was. When I add the curve modifier it rotates it slightly but nothing else. I'll attach the blender file (~900kb) so you can see exactly what I mean. Here is the link: https://drive.google.com/file/d/1cxgDtm2K-N7xxrM9HdsopXwDzs1MIFWJ/view?usp=share_link
ok, that was a trickier one ;)
The problem with your curve(s) are: It's not just one part, they consist of two parts.
You can verify this by selecting the curve and press ".". Then you will see that the curve isn't really centered. One easy way to fix it is: With your blend file opened, just add a cube, then press "." so that the view gets centered around the world origin. Then press x to delete the cube. Now you see there the rest of your splines.
Select it in object mode, go to edit mode and just delete the vertices (do these for the other curves as well).
Then it works.