Try changing & reloading the mesh settings back and forth, to see if it kicks the bridges in. I've had it appear flat once or twice. Unless you actually selected the wrong option in the installer? You'll need to re-install & select correct option.
The reflectors have LODs which might kick in to early if zoomed out. The Microsoft LOD system is based on 'pixels on screen' not 'distance to camera' like it should be. A horrible system.
Anyway, I've attached new reflectors without any LODs. They should render from any angle, zoom lever or distance. Only side effect is they might flicker a tiny little bit in the distance.
I think you are using FS9? That file is for fsx so probably wont work. The shadow i recall does work on the bridge but not perfectly. It might have different results in fs9. I dont have fs9 installed right now to confirm it.
What is your problem JMD? The Taxiway reflectors have a patch above.
If you have a flat bridge, re-install the scenery & make sure you tick '3d bridges'. Setup your FSX Mesh resolution setting like the manual says. 5, 2 or 1m If three's still problems, it could be caused by third party terrain, afcads or old scenery you forgot to un-install. Reboot it.