LED Lanterns

What do the flashing red, yellow and green lanterns indicate?

which ones? these?

Yes

We didn't use them on the LIRR. I'm curious how they're used on the TA.

Those lanterns are used to guide trains through work zones. If you see a yellow lantern, it means there is MoW work or workers ahead. If you see a red lantern, it means do not proceed. If you see a green lantern, it indicates the train has exited the work zone and can resume normal speed.

Thanks Joe.