Purpose of red Mars Light and Beacon on F40PHM-2s?

While going thru some old pictures, I noticed the F40PHM-2 locos working on the BN line have red beacons next to the orange one and a red mars light next to the white/clear one on the roof.

Older photos show them still installed, but I have not found a photo of either in use. What was/is the purpose of the red beacons and Mars lights?

The red beacons are for freeze protection. When the units are shut down and plugged into wayside power at outlying yards, they have a layover system that keeps their fluids warm, batteries charged, etc. in the winter. If that system fails, the red beacon will activate to alert nearby employees before any damage occurs.