Alpha 69 high bridges crash

[3iff]

When trying to build a bridge spanning the gap as marked with the white line, I get a crash to desktop. As far as I can tell, I'm not trying to do the impossible...(unless I'm mistaken!).

A69, winttd, , crashlog, savegame and configs enclosed. I'm using the Canadian set (the one prior to the latest release). I've tried switching the trainset to standard, moving the date to 1950's and building a different bridge but with no effect.

If I fill in the small 'hole' then a standard single level bridge builds normally.

Incidentally, when I get a ttd crash, I have to reset my machine. If I don't and restart ttd, the system locks up. Using W98se and there are no strange tasks running on my system...I shut down all unnecessary tasks before starting the game.