I have noticed strange behavior when removing bridges. The road on the slope (bridge ramp) is left in place, but disconnected from the rest of the roads. Tested on pak128.britian-1.15, but I think it is error in the simutrans engine.
How to repeat:
Lets build bridges by dragging (no previous roads on the place): (https://uran.webstep.net/~vladki/simutrans/bridge1.png)
Then delete the bridges - road on the bridge ramps are left in place, but the road conecting the two bridges disappeared. (https://uran.webstep.net/~vladki/simutrans/bridge2.png)
Rebuild the bridges (the road in betweeen them had to be rebuilt manually), and build some more roads leading to the bridges: (https://uran.webstep.net/~vladki/simutrans/bridge3.png)
Delete the bridges again, and you will see the road in the left corner disconnected: (https://uran.webstep.net/~vladki/simutrans/bridge4.png)
I think the road problem is that deleting the bridge removes the road connection between the ramp and next tile. I think it should be better to simply remove the road on the ramp tile.
I notice that the behaviour is different for bridges built raised over flat terrain compared to bridges spanning a valley. In the former case, two road tiles are left behind at each end.
Yes the behavior on flat land is different, slightly better, but still wrong IMHO.