Oooooohhhhhh i've found something interesting.
Orange sodium catenary lighting illuminates the M62 passing through the M61 interchange. I really love this image.
http://www.cbrd.co.uk/media/photo/15/18.jpgI remember those well! The lanterns were Philips MU62s (IIRC) and they used to fascinate me as a child. When my parents and I used to travel to Nottingham to see family via the M62 and M1 I used to always love seeing these as it meant we were well on our way and leaving the North West! (Not that there's anything wrong with the North West you understand
) I think they were taken down in the mid-90s and replaced by ZX3s (boring!). The other lanterns on columns (S&L by the look of them) were Philips SDP254s, they were the favoured motorway lanterns before the MA60 came along. They looked very similar to the MU62 lanterns.
M62 passing the farmhouse in the middle, note the road is unlit.
http://www.cbrd.co.uk/media/photo/15/11.jpgI remember this being unlit as well, I think it became lit in the late 80s or early 90s as I remember my dad mentioning there was now lighting over the Pennines on the M62 where there hadn't been previously on one of our Nottingham excursions.
When I was at Uni (in the 1990s) I read a book about lighting design (well, the street lighting bits because that's what interested me!), and the subject of terminating lighting, and how to do it well, was discussed in great detail. They believed the best solution for twin or opposite lighting arrangement (i.e. double brackets along the central reservation, or pairs of columns placed opposite each other on each verge), was to deliberately illuminate a specific light-to-dark 'transition area' using just the light spilling over from the other carriageway. This would be achieved by ending the lighting on your side of the road before the lighting on the other side was ended. The overspill light from the other side would be enough to provide a lower level of illumination for the few seconds you need for your eyes to adjust to the dark.
As far as I understand, there are no such issues going from an unlit section to a lit section of road, so there is no need for a dark-to-light transition area when entering a lit section of road.
On an opposite arrangement, the columns on your side of the road would end sooner than the other side, and on a twin arrangement, the last few columns would have single brackets pointing to the other side. There would be no need to adjust the column spacings, and no need different wattage lamps.
Despite it being such a simple and, dare I say it, obvious solution, I don't ever recall seeing it in real life, either before I read that book, or since.
That's very interesting and a sensible approach to take and no, I've never seen it executed anywhere either! They would rather plunge us from blinding orange SON light into total darkness without any warning or transition period!