Shadows in Tunnels

After importing my routes into TRS19, I'm noticing shadows from content (including trees and shrubs) appearing inside the tunnels. I've also noticed that one wall and the roof of the tunnel is dark, while the other wall is light. I haven't really run my routes a lot since adding TRS19, so this problem may have come up before in the Forum, and, if so, I missed it.

Are any steps being taken to correct this problem?

Thanks,

Joe