One pair (2) HO scale crossing gate signals by NJ International, Inc. Modern pedestal type base with red & white gates with 'A' type arm that swing freely and can be animated. Nice detail. Brass construction with 4 LEDs (2 in each direction) and the necessary dropping resistors installed.
Detect trains and animate these signals with the GCP Grade Crossing Pro controller by Logic Rail Technologies (sold separately).
Animate the crossing gates with Tortoise #800-6000 slow motion switch machines from Circuitron (sold separately).
Add realistic sound to your crossing signal with a Grade Crossing Bell sound module from ITT (sold separately).