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 Post subject: Re: Motorway Lighting
PostPosted: Sun Dec 06, 2009 10:47 pm 
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Gramma6 wrote:
600w lighting is certainly never necessary! 180w SOX is fine, it lights the motorway well when installed correctly.


I agree. I was shocked to discover that the Sapphires used on the M1 widening scheme (just north of the M25) take 600w SON-T lamps! Unbelievable.


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 Post subject: Re: Motorway Lighting
PostPosted: Sun Dec 06, 2009 11:55 pm 
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Alex wrote:
Gramma6 wrote:
600w lighting is certainly never necessary! 180w SOX is fine, it lights the motorway well when installed correctly.


I agree. I was shocked to discover that the Sapphires used on the M1 widening scheme (just north of the M25) take 600w SON-T lamps! Unbelievable.


Does that include the twin arm brackets?

I urge everyone to be vocal when the subject of the environment or light pollution is brought up on the radio.

Time to get people aware and show up the Government yet again.


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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 12:59 am 
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Stelmer... If the HA are doing work in an area, they may have a compound locally. There is a works unit a few junctions further south on the A1(M) that is on a hill above the road, and can be seen from the carriageway.

It'd be good to get all of them tunnel lights!

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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 1:14 am 
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With reference to the 180w SOX lanterns used for motorways, I have a nagging doubt in the back of my mind that there might be statutory minimum mounting heights to adhere to when lighting a motorway, and the minimum mounting heights are usually dictated by how wide the motorway is. Feel free to correct me if you think what I am about to say is not true!

The usual mounting height for a two-lane dual carriageway is 10 metres with 135w SOX lanterns, and for a three lane motorway it is 12 metres with 180w SOX lanterns. If I recall correctly from my Uni days, a four-lane motorway (which was still quite a new phenomenon in the 1990s) requires a minimum mounting height of 15 metres, which excludes SOX as a light source because there isn't another step up in the wattage to do the job. I think this is borne out in practice, because I have never seen a four lane motorway lit with 180w SOX.

So the question is, can a four-lane motorway conceivably be lit by 180w SOX at 12 metres, or would the lighting level at the hard shoulder be considered too dim? If the answer is that SOX cannot be used for more than three lanes, then that would explain why so many motorway widening schemes, for example the M1 between the M25 and Luton, would have not been able to accommodate the reinstatement of SOX, even before SOX was ruled out on the grounds of its colour rendering.

My understanding, which may be based on the lumen charts of yesteryear, was that 250w SON is equivalent to 180W SOX, so a three lane motorway would have 250w SON at 12 metres. Therefore, is the Highways Agency just stepping up the wattage for every step up in the mounting height, e.g. 400w at 15 metres for a four lane motorway and 600w at 18 metres for five lane motorways? Is stepping up the wattage for every step up in the mounting height a crude way of doing things, or is it a logical thing to do? After all, SOX doubles from 90w at 8 metres to 180w at 12 metres, so SON going from 250w at 12 metres to 600w at 18 metres is almost a doubling of the wattage, but with a bit on top for future-proofing!

This is just a theory for why new motorway lighting seems so excessive.

There is a section of the M5 in Birmingham where 180w SRS201s / MA60s are mounted at 15 metres, and they do a perfectly adequate job of lighting the motorway (although, if my memory is correct, it is only 3 lanes wide in this location). 15 metres is, after all, only 3 metres above their usual mounting height so the illumination level, I would have thought, isn't going to be significantly reduced.


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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 8:28 am 
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180w SOX has been used for four lane motorways in the past at 12m mounting height - catenary lighting. Earlier catenary lighting was single lamp, and later they used twin lamp Phosco P415s.

250w SON may be a closer match for 180w SOX in terms of lumens, but the whole matter of a fuller spectrum not actually requiring as many lumens to produce perceivably the same amount of light has been overlooked. For example, I have seen a few locations where 180w SOX has been replaced by 150w SON, and the 150w SON does a good job at 12m. It may not be as bright as 180w SOX, but the quality of light is better, and remember, the argument that 180w SOX produces more lumens is the same argument as 600w SON produces more lumens; the argument that more is better.

The HA goes for a minimum of 12m columns on dual two lane dual carriageways nowadays, even though you could light such roads perfectly well with 10m columns. I have even seen 15m columns on such roads, giving a mounting height to road width ratio of 2:1. I believe optimum lighting is provided by a ratio of 1:1, so a dual two lane dual carriageway would be optimum with 10m columns. A dual three lane motorway would need 12m columns, and dual four lane would need 15m columns.

The British Standards, and HA, are fixated on lumens though. As mentioned, I've seen 150w SON at 12m height, and it works. I've seen 250w SON at 15m height, and that works. When the A27 in Portsmouth was widened in around 1979/80, the dual four lane section was lit with 15m columns with 400w SON "Turtles". Bear in mind, modern optical systems are supposedly more advanced and therefore shouldn't need to compensate with brighter wattages nowadays. Also bear in mind that in the old days SON lamps weren't as efficient as they are now. For example, back in 1973, a 400w SON lamp was roughly as bright as a modern day 250w SON lamp. So surely, if 15m columns with 400w SON was good enough back then, 15m columns with 250w SON should be perfectly adequate now.

You could actually put 180w SOX at 15m height. From experience of driving on 180w SOX lit motorways, the motorways are absolutely bathed in orange light. It may be monochromatic light, but it is far from dim. Mounting the lanterns 3m higher and widening the column spacings would make little difference to perceivable lighting levels, and just spread the lighting further. Bit like in Portsmouth where in some places 70w SON has been mounted at 7m height. Just means the uniformity is better and you don't get such bright patches directly below the columns.

We can thank the British Standards for street lighting overkill. Even 30 year old SOX installations on motorways, in my opinion, have columns spaced closer together than really necessary at around 1:3 height to spacing ratio. On the M1 the old columns in Northamptonshire have a height to spacing ratio of around 1:4, yet they still do a perfectly good job. Even 1:3 spacings are starting to be considered too large nowadays though, which is madness.


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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 1:02 pm 
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Alex wrote:
Gramma6 wrote:
600w lighting is certainly never necessary! 180w SOX is fine, it lights the motorway well when installed correctly.


I agree. I was shocked to discover that the Sapphires used on the M1 widening scheme (just north of the M25) take 600w SON-T lamps! Unbelievable.


This was the motorway we used to get to Luton, and for some parts of the motorway, there were 600w SON Sapphires on the verges as well as the centre. I don't see how this is energy efficient at all.  :?

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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 1:04 pm 
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Stelmer wrote:
Alex wrote:
Gramma6 wrote:
600w lighting is certainly never necessary! 180w SOX is fine, it lights the motorway well when installed correctly.


I agree. I was shocked to discover that the Sapphires used on the M1 widening scheme (just north of the M25) take 600w SON-T lamps! Unbelievable.


Does that include the twin arm brackets?


Yep, double brackets, and as I mentioned in the last post, also, there are Sapphires on the verges for some of it too [as well as the double brackets] so just one row of lanterns across the road would use 2400w  :shock:  :shock:  :shock:  :shock:

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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 1:41 pm 
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This source suggests that the average UK household uses 4400kWh of electricity per year, which averages at around 12kWh per day. It only takes 20 columns fitted with 600w SON lanterns, excluding gear losses, to be switched on for one hour per day to match the same power consumption as the average British household. The old 1970s lighting on the M1 in Northamptonshire features around 40 columns per mile. I've counted, and that means column spacings are around 45m. Column spacings that the HA uses for 15m columns nowadays are typically 50m, so not much greater. Hence, one mile of 600w SON switched on for one hour per day uses around the same amount of energy as two households per day by my reckoning, excluding gear losses. And the government has the front to tell us to save energy.

phosco152, please check my calculations to make sure they are correct so that I don't end up with egg on my face!


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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 3:42 pm 
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I've seen SOX used on multiple lane motorways, be it a small part.

The M60 at J14/15 I think is part SOX and is illuminated fairly well.


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 Post subject: Re: Motorway Lighting
PostPosted: Mon Dec 07, 2009 4:57 pm 
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sotonsteve wrote:
This source suggests that the average UK household uses 4400kWh of electricity per year, which averages at around 12kWh per day. It only takes 20 columns fitted with 600w SON lanterns, excluding gear losses, to be switched on for one hour per day to match the same power consumption as the average British household. The old 1970s lighting on the M1 in Northamptonshire features around 40 columns per mile. I've counted, and that means column spacings are around 45m. Column spacings that the HA uses for 15m columns nowadays are typically 50m, so not much greater. Hence, one mile of 600w SON switched on for one hour per day uses around the same amount of energy as two households per day by my reckoning, excluding gear losses. And the government has the front to tell us to save energy.

phosco152, please check my calculations to make sure they are correct so that I don't end up with egg on my face!


20 columns (1/2 a miles worth) at 600w each is 12Kw load so for 1 hour of use that is 12Kwh, so over a year that is 4380 Kwh. So yes about the same as the alleged household use for 1 year. However if they are twin brackets that is 48Kw load or about 4 houses per mile for 1 hours use! It is worse than that if you include gear losses.  :? This is absolutely appalling and why further lighting of motorways 24/7 cannot be justified. Some of the busiest sections of the M3 and M4 are unlit for instance. This environmental impact cannot be justified in the name of reducing accidents especially when vehicle safety is improving all the time.

To validate the household figure - I pay my electricity by direct debit. They have just calculated my payments for the next year based on a usage of 2280 Kwh. That should have been based on last years usage - I've been in the house more than a year now. I am not on a gas supply so have oil heating and use electricity for cooking/electric shower etc. I am the only occupant, so assuming 2 people in the household, energy consumption would be perhaps 30-40% more ( 2 people doesn't necessarily mean double the lights for instance..), so the quoted figure of 4400 kWh is probably about right.


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