New AI line + hints for Portland International Raceway by Simtraxx.
This AI file makes the track drivable against AI as it defines new side borders. Perhaps it won't work after another update, keep that in mind. The track is still in beta status.
You can get beta access to Portland (and other tracks) on the simtraxx site. I cannot and won't post a download link as the track is not freeware right now.
Just unzip and copy the specific track folder to your assettocorsa\content\tracks, it will automatically copy the new ai + hints to the correct folder. Perhaps make sure to keep your old AI files if you don't like the new ones.