I am building my own Battle Royale map with a large road network. I found a way to build tunnels and caves under and through the terrain instead of having to use terrain objects over an existing valley. I was able to do this by simply making holes in the terrain surface using the visibility tool under the sculpt tab in landscaping mode; I then just used indestructible pieces to close up the gaps and line the inside of the tunnel, and finally stretched some road splines through the tunnel with landscape deformation turned off.
Visually, the tunnels work perfectly, gravity works as normal inside them and I am able to walk through them as a player with no problems. Vehicles, however, are incapable of passing through them fully. Whenever I tried driving a car through, it would glitch up through the ceiling of the tunnel and onto the terrain surface above. This is not just an issue with a specific vehicle though. I used the Whiplash, Prevalent, Dirtbike, Mudflap, and even an airplane, but they all had the same issue.
I tried fixing it in several different ways like making a second terrain surface the floor of the tunnel, but that didn’t work either. My best guess is that it is a limitation of the current vehicle physics where the vehicle must be either contacting the terrain surface, or an object above the terrain surface; not an object or surface below the terrain. Perhaps it could be fixed by modifying the way vehicles react with terrain through scripting, which I unfortunately know nothing about.
There has to be some way to make it work though; Epic was able to do it in locations like Rave Cave and the caves behind Reality Falls from a few seasons ago, and Shattered Slabs from the current season, which, I am almost certain, used the same method as I used to build an underground area. I know from firsthand experience that vehicles could drive through these locations.
I would greatly appreciate any ideas or fixes for this issue.
