I realise that this is a very controversial topic just now, but hear me out.

My thoughts on LED street lighting are the same as a lot of people on here. They are worse than useless, and here is why I think that's the case:

I'm using some figures here that aren't real world ones, but make the mathematics easier on my brain. And I'm probably going to use some terms that aren't proper ones. Replacing a 100W Discharge lamp with an LED fixture of 90W will save you money undoubtedly, but the lighting level is going to be a lot lower than merely 10%. And that is because of physics, in the discharge lamp you have 1 element pushing out 100 Watts, and in the LED fixture you have 10 elements pushing out 9 Watts separately to make up the 90 Watts. That is why they are such glare bombs and have poor light projection, there's no problem in enclosed spaces, but once you get out into the great outdoors you're in trouble.

Then why did I measure with my light meter 20% more light falling on the street when a 100 watt HPS was replaced with a 47 watt LED? And 9 watts is a lot for an LED emitter, typically they're more like 3-4 watts.

None of the full cutoff Xcel or MnDOT LEDs glare nearly as much as the semi-cutoff HPS lights they replaced. Although the American Electric ones with the exposed glass optics are close.

I said that I wasn't using real world figures. And the LED fixtures they have over here don't have any type of diffuser to help spread the light. It may just be down to poor planning of the installation that they don't work properly.

What kind of fixtures are these? If a 90 watt LED fixture gives less light than a 100 watt HPS fixture, they must be using unbelievably terrible LED fixtures, considering here they replace 100 watt HPS with around 50 watts LED and get more useful light on the road.

I stated in the OP that I wasn't using real world figures, it was just a hypothetical setting to make the mathematics easier on my brain cell. Whatever the fixtures they have here were used, in our opinion whoever 'designed' the installation should be ashamed of themselves.