Southern Pacific units and all the crazy head lights

Just wondering what was the deal with Southern Pacific and all the different light configurations what did the red lensed head light's serve on there units? and what is this big trash can light for on this SD unit?

The SD7 picture was backup power for the Bay area commuter service( s/g exhaust visible behind the early model Gyralight). The "Ash-can" light is an early model Gyralight.
SP power typically had a two lamp headlight, a two lamp Gyralight, and a single lamp red emergency light. The Emergency light activated whenever the air brakes went into Emergency to warn any approaching trains that derailed cars might be fouling adjacent tracks. Since many end cab switchers were used in road service on weekends, they also received full light packages.

The red "emergency stop" light also made its way to Amtrak diesels, including the F40PHs, the Dash 8-32BWHs, and even the first batch of Genesises. Eventually they were removed from the Dash 8s and the Gennies, but many of the F40 NPCU rebuilds still have them, and they still work.

I take it that SP was into safety with all these different lighting set ups and so forth?