I had the MTH premier IATD's and was frustrated for weeks trying to get them to work right. The lighting was the problem. They would work great when it was dark.
For my crossing gates, I just use the simple method of the isolated 3rd rail. It's simple and it works every time.
For my overhead signal bridge I went with the Z-stuff sensors. They have been working fine for me. Skip ahead to :48 if you don't want to watch the whole video.
Have Fun
Ron