Hi! I think the sign with "crane overhead" was to subtle for me, because I was thinking "Oh, should I use the crane? Nah, they'd make that more obvious!" 😅
The routes I had the hardest time finding was in Act 2, the one that opens the first wall, behind some kind of gigantic digging machine. I did not figure out how to get there, I drove under the machine and got airlifted to the site from there. I think I left be crashing down a slope. Act 2 was a lot of "crashing down slopes" for me, not sure why I did not see the roads. The other one that was hard was to the very last one in Act 4.