TL;DRShow some type of numerical indicator when placing new signals/stations, for how many train cars can fit.
The current system is limited to 5 train entities, and if it were more they would still have to be counted.
What ?When placing a new signal or train station (or ghost), numerically display how many train cars (regardless of type) can fit between the potential placement, and the next signal/station behind it.
Why ?Visual feedback is king.
Showing 5 train cars is helpful, but seeing something numerical would be more helpful, especially for trains of long length.
This would no longer require numerous, pre-made blueprints or massive clearing/landfilling for every possible scenario. Placements of actual trains for measuring would be unnecessary, which could potentially interfere with tracks currently in use if you even have the trains in your inventory. Trains whose lengths are greater than five could be planned out on-the-fly.
Players can place an initial signal, and the interface helps along the way. They can subtract double-headed trains or extra cargo wagons in their heads for curves pertaining to loading/unloading, or place an extra signal to get a new calculation displayed.
Something succinct, but I'm sure someone else has a better idea than my mockup. If the number was within the train car it would be clean-looking, but I'm not that talented with photoshop.