Bigger pbs blocks

[avdg]

At openttdcoop I had noticed, that we sometimes are using big pbs-blocks with only a few junctions... I know from the reservation that the reservation is tile-based, but I'd discovered too that the pathfinder is tile-based too (by looking up in the source). Then I've started to think that if you are using pbs-blocks in stead of tilereservation. But should that use much memory, and should it really improve the performances? I know too, that it will need a completly rewrite of the source... That's why I keep it by a suggestion.

My plan:
-group all tiles from junction to junction and keep a list of all special items (crossover, 90° curve, ...)
-junctions, signals will be nodes, so all these groups has to be connected to a node
all these items are in blocks (like train control systems in real life)

at normal cases, this system will not affect the reservation, it is only a other system

the reservation will be cleared if a train left the hole block.

Why should it work faster:
-The pathfinder should be able to find quicker a reserved path
-All actions of a group should be called directly, without scanning these tiles
-A train reserves only groups, and not tile by tile

[avdg]

Added image to show my idea