ive notice at night times on services on Xbox one when you have headlights on you can't even see in front of you. For example GWR you can even see there tracks until your at the station
The purpose of headlights on UK trains is to be seen rather than to see. Headlights in TSW are not really that great generally and I know there's been a lot of criticism from US train users about the poor lighting. I'm not sure how much of the issue is down to the underlying engine (UE4) and how much is down to poor implementation by DTG.
UE4 can't handle bright light sources without loosing color and DTG is compensating for it by making the lights less bright. Replacing the tonemapper with something that can handle bright light sources (Reinhard, Drago,...) would not only fix this problem and allow DTG to make properly bright headlights but it could also improve visuals at no performance cost.