Oh sorry, I should have been more preciese.
What I was refering to is not multitile in width but in length. In extended, there is a difference in between pillar bridges (cannot be built above deep water) and spanning bridges (have a maximum length restriction)
What I thought about was rendering spanning bridge images specific to different lengths, always including a single tile segment.
The game would then always place the longest segment available in the middle and then continue left and right by always placing the longest possible segment until the whole bridge has been built.
That would also require multiple sprites in height, as spanning bridges do usually have very high supports that exceed a single sprite by a lot.
Multitile in width would be nice either, but I did not have this in mind originally.
About these points:
a) is indeed an issue. Strictly splitting the bridge into graphics below (minimum) way level and graphics above (minumum) way level might help here. That would as a sideffect also help to get a bridge starting with a slope when the terrain underneath is not flat.
b) The spanning bridge ends at the elevated way, so no problem.
c) As described above, the longest possible segment will always be built in the middle, expanding from there to both directions by always picking the longest poissible segment.
d) In extended, ways are already split from bridges and tunnels and Imho this feature might be a good idea for standard too. However, elevated ways and tunnel portals do not split this graphically yet, I don't know why.
