I've been driving some of the SKA s-bahn services recently and I've noticed that they all crash around the same spot on the approach to Köln Hansaring (heading to Hbf). This only seems to happen if I've done a service from Köln Hbf to Düren or Sindorf, then another back to Köln Hbf. For example, I was driving the 09:16 service from Sindorf to Blankenberg (probably) and the game crashed when I was about 60 metres from Köln Hansaring. I'm on a standard PS4 and have all layers activated for SKA.
Just something that may point at an asset to investigate here - I get issues on PC when the tower cranes are loaded into view at Koln-Ehrenfeld. Not a crash, but a stutter or freeze. - its always when trying to load those tower cranes.