It would be good for some routes to have more options for scenario planner such as a passenger path for Cajon Pass from San Bernadino to Barstow, a path from Birmingham New Street to Bromsgrove that goes through the passing tracks at Kings Norton and Longridge. Another thing that scenario planner should use are the portals so any AI you place ahead of the drivable train can head off the map and avoid blocking the path.
Honestly the entire scenario planner needs to be completely reworked from the ground up to be more like TSC. I know that's not what your suggesting but I feel like I should just input the entire planner as whole. But yeah I agree with the fact that these major routes don't have proper ways.
