I must have used the wrong ID when i copied the original node. Seemed a bit odd it generated an error in the .dat instead of the .val.
In the visual damage node theres an id that starts 0x8bd48 and a parent id that starts 0xbc63 ( which i think is the hull id ), so in the node i copied i set the id the same as original 0x8bd48 and the parent id to 0x10a1adb6d12c1100 which is the id ( but not the parent) for the bridge.
The parent id's in the sub catagories that display the parameters have been left identical at 0x8bd48.
I hope that's right

, i've only been experimenting with zones and their parameters in the main hull up till now, so i've not had to mess with model id's, particle id's or any other id's.
It doesn't generate errors any more, but collisions still don't show up, despite adding spheres to the bridge.
It would be nice to get impacts to show up because it would help me determine what exactly causes the bridge to disappear, but theres something about the bridge setup i've obviously not twigged yet, that's completely seperate from the visual damage effects.