flashing crossing signals

[Philip H]

It's because they're real bulbs, which are probably being run under their rated voltage. The fade-in-fade-out is filament warm-up time, then cool-down. If you replace with LEDs, you'll get the abrupt on-off-on-off.

Getting fade-in and -out is definitely doable with LEDs. There's the Ngineering module (cheap, and I have had nothing but great results with his circuits), and then there's Max's approach with the capacitors.

Which Ngineering module?

[C855B]

N8038 - Early-era Alternating Flasher Simulator - http://www.ngineering.com/lghting%20effects%20for%20the%20railroad.htm#EarlyaltRR