I found the following in way/roads.dat:
QuoteObj=bridge
name=ClassicRoad
waytype=road
copyright=Hajo
cost=20000
maintenance=2000
topspeed=80
max_lenght=7
intro_year=1920
retire_year=1919
What does it mean when the intro_year is after the retire_year? The effect seems to be that it is not available in any year. If so, why is it even there?
Also, I would assume that it's too late to correct the typo in max_lenght? I cannot imagine that it's remained unnoticed for all this time, so I assume that it's impractical to fix it, for reasons of backwards compatibility?
As I understand it, I might even have been told it when bringing up this earlier, this type of bridge is no longer officially part of pak64. It is just present so that old games using it still work.
It is possible to fix the typo. Makeobj reads both the right and the wrong spelling. I'm not so sure about other third-party tools operating directly on the dat files, though.
Wouldn't it be better to use compat.tab settings to make older saves load officially supported bridges of closely matching speed and design?
Maybe there was no compat.tab back then. Someone more knowledgable about Simutrans' history will have to answer that.
I think there are a few other strange things in pak64, like graphics without a dat file. There are also a couple of industries that will never appear in new games.
I think this was purely for compatibility. Another way this can be done is to have no icon graphics.