I noticed ALL but one of the HPS lights on the intersection of 285 and Colorado 8 now make a white light. Not the yellow light of HPS. ALL of them have a white MH or MV color. could they all have retrofits of MH on the HPS ballasts? hmm... Every one is like this except the M-400 a1 FCO, which stil makes a yellow HPS...

All of the lights still have the yellow 40 NEMA tags.

I've also seen HPS lights that were a white MV/MH like colour, I find they are usually the cycling ones are yours cycling at night? They could have MH retrofits installed in them but that's pretty unusual for them to do that. Here's a example of a MH retrofit lamp for HPS ballasts in Darren's collection.

I think they have mh retrofits inside them. All of them are 400w HPS ballasted fixtures except for one which is 250w and doesn't have a retrofit and is still hps. Some of the lights that were out work now with the mh color. I like the white instead of the yellow HPS. I would need to get a closer look at these anyway.   

I think they could be anti cycling Hps lamps at Eol or if they just were like that one day, then the ballasts or retrofit lamps were used.

In Worcester, MA on I290, the HPS lights that we have were relamped with MH bulbs a few years ago. After about a year of these MH bulbs failing miserably, they were relamped with their HPS bulbs again.

I think they could be anti cycling Hps lamps at Eol or if they just were like that one day, then the ballasts or retrofit lamps were used.

I doubt all the lights would go at the same time.

Are there any advantages of HPS over MH or vise versa?  I have converted several HPS lights in a warehouse to MH because the color of HPS SUCKS to work under! This was a clothing warehouse, so it was hard to distinguish the colors under the yellowish light. I know the HPS fixtures were 150 watt and the MH were 175 watt in this example, but what is the advantage/disadvantage in road/yard lighting?

Are there any advantages of HPS over MH or vise versa?

HPS: Cheap lamps, efficient, quite long life (limited by thermal instability, so annoying cycling EOL behavior - need to be addressed by the gear intelligence, like ignitor cut-out timers), self-compensate for lumen loss over life (on most ballasts increase it's real power input, as the lamp age), however very poor color rendering

White-SON: High quality really warm white light (the only HID available for CCT<3000K and CRI 90+), expensive lamps, quite short lifetime, complex gear (require active arctube temperature stabilization, as inherently thermally unstable), not as high efficacy

QMH-probe: White light with moderate CRI, relatively simple ballast in US (in Europe require ignitor as HPS or pulse-MH, so no advantage here), not as expensive lamps, medium lifetime, poor efficacy (worst "of this list"), life rating exaggerated due to the high lumen loss - economic life (when limited by 70% lumen output) is quite short, high risk of non-passive EOL behavior - need protection

QMH-pulse: Not as much expensive lamps (but more then HPS), quite good efficacy, in Europe compatible with HPS gear, if it is thermally protected, medium quality light (CRI 70..80), not so stable color, life not as good (limited by lumen drop), high risk of non-passive EOL behavior - need protection

CMH: Quite expensive lamp, high efficacy, quite long life (but not as HPS) good CRI (80+) for 3000K and below, excellent (90+) for ~4000K, stable color, not available in >4500K, some risk of non-passive EOL behavior - need protection

Wow1  Thanks for the detailed description!

Are there any advantages of HPS over MH or vise versa? 

HPS

+
Higher wattage HPS is pretty similiar in efficacy to state of the art fluorescent system and lumen maintenance is 80-90% as opposed to 50-70% for MH.

Better fog penetration due to longer wavelength, like yellow fog lights
faster restrike

-
Low CRI
efficacy not as good as LPS

MH
+
higher CRI, white light

-
poor lumen maintenance
lower efficacy