I have the log now, but it's obviously much too large a file to upload here.
Apparently the signal bridges I'm missing appear to be sourced from Kuju, but I am missing the files. A few examples:
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailSimulatorUS\RailNetwork\Signals\US Modern\Post\smm_uss_cantilever.bin,(Scenery Item) on tile -000073+000058.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US BNSF Post 1 Head 0T Tall.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head 2T Tall 60-50.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head 2T Tall.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head 2T Tall.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head 3T 2E Tall.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head Special 1.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\US Def2 Post 2 Head Special 2.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Signals\US Modern\Post\USmod_pt1_tll.bin,(Scenery Item) on tile +000012+000080.bin,,,,
As for the Junctions missing ties and stuff,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Junctions\aaaaa.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Junctions\High_Target_Switch\HiTgt_Manual_NoRod.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Junctions\Manual_junction_Lever_1.bin,(Track Item) on tile Tracks.bin,,,,
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\Kuju\RailsimulatorUS\RailNetwork\Junctions\PRR_MnlSwitch_GR1.bin,(Track Item) on tile Tracks.bin,,,,
Apparently I'm missing a LOT more stuff but I'm only really concerned about the switches and the signal bridges.