Lighting one side of a dual carriageway

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Chris5156
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Lighting one side of a dual carriageway

Post by Chris5156 »

Recently I've come across several locations where the full width of a dual carriageway is lit by one row of very powerful streetlights at one side of the road - nothing in the central reserve, nothing on the opposite verge. I guess this saves installation and maintenance costs, and possibly power consumption too.

There's two on the A1 that I passed last night - one between Tempsford and Sandy (too recent to appear on Streetview) and another here near Hendon. These are managed by the HA and TfL respectively, so it's clearly not one highway authority's trick. The Hendon one is particularly noteworthy as the lights also supposedly light the parallel service roads - a total of four carriageways - but don't seem to do a very good job of lighting much beyond the northbound carriageway in reality.

Is this a new recession-friendly technique for lighting dual carriageways? Are there more examples?
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Johnathan404
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Re: Lighting one side of a dual carriageway

Post by Johnathan404 »

It wouldn't just save on the obvious maintenance cost, but it also means you can also access them with only a single lane closure (if that, depending on how much verge is available and whether you needed to get to the lamp), as opposed to two outside lane closures for central reservation lighting.

Have never seen this design though.
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Re: Lighting one side of a dual carriageway

Post by Haydn1971 »

That's a long throw to reach the opposite kerb !
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Re: Lighting one side of a dual carriageway

Post by Bryn666 »

I've seen it done in France but not the UK, suspect as Haydn says light spill is actually not that great.
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Re: Lighting one side of a dual carriageway

Post by M56phil »

The A34 just south of the M40 junction heading towards Oxford has a short stretch of 'one sided' lighting on mainline D2 A34. I think it's SOX lighting if memory serves.....
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Re: Lighting one side of a dual carriageway

Post by Chris5156 »

Haydn1971 wrote:That's a long throw to reach the opposite kerb !
Certainly is! If you follow the road south on the GSV link I posted, you'll see the lights run on both sides of the road once you approach the next set of lights, and where there are lights on both sides the columns and outreach arms are half the size. Those are some huge streetlights on the one-sided section.

But it's a big job to ask no matter how tall the column and how bright the lamp, and I really don't think it does the job for a four-carriageway road!
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Re: Lighting one side of a dual carriageway

Post by boing_uk »

Haydn1971 wrote:That's a long throw to reach the opposite kerb !
Not really with proper choice of lantern and reflector design. You can get surprisingly defined light spread.

Bit like these babies in Grimsby. There's another bridge further east lit the same.
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Re: Lighting one side of a dual carriageway

Post by Haydn1971 »

I'll reserve further comment until I've seen them in the dark ;-)
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Re: Lighting one side of a dual carriageway

Post by boing_uk »

To be fair it's not bad on the ground... lighting levels are exactly what you would expect.

It just looks different because the light source isn't nearby.

Given the classification of the road and knowing the lighting engineers there, I have more than every confidence that lighting levels are to standard.

Of course, if I can find the time and inclination, I'll get pics while I'm home for Xmas.
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Re: Lighting one side of a dual carriageway

Post by sotonsteve »

At M25 J5, heading anticlockwise, as the slip road for the M25 peels away from the M26 the columns in the verge of the M25 slip road also illuminate the eastbound carriageway of the M26.
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Re: Lighting one side of a dual carriageway

Post by Patrick Harper »

I'm sure a small section of the M6 in Cumbria had one-sided lighting, but that was 2 years ago now. I believe they are GEC SON vintage, and probably for maintenance purposes.
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Re: Lighting one side of a dual carriageway

Post by poshbakerloo »

Why didn't they just put them down the centre.
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Re: Lighting one side of a dual carriageway

Post by Chris5156 »

poshbakerloo wrote:Why didn't they just put them down the centre.
I suspect two reasons - one is that lights on the verge are easier to reach and maintain than lights in the central reserve (in particular, the example I posted of the A1 at Hendon has an extremely narrow central reservation and you would have to close a lane to reach the lights if they were there). The other is that both examples I posted had lights down the side verges before, and when the new replacements were put up, running a new power line down the central reservation would have been a significant cost when the object seems to have been saving money. Running the single line of lights down one side would have re-used an existing cable run.
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Re: Lighting one side of a dual carriageway

Post by Chris5156 »

*Bump*

I've found another example of this, from a different authority again. The Skanska lighting PFI operating in Croydon has put new lights up the A212 Gravel Hill, a dual carriageway on the outskirts of Croydon, which run only on the right-hand side of this view. They're tall with a short outreach arm and are obviously intended to light the whole road.

The example in my original post, the A1 at Tempsford, is now on Streetview - you can see there's just one line of lights there too.
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Re: Lighting one side of a dual carriageway

Post by Bryn666 »

The A212 columns are Stewart and Lloyds from the 1950s; shame they're gone. Similar to what Birmingham used to use.
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Re: Lighting one side of a dual carriageway

Post by Chris5156 »

Bryn666 wrote:The A212 columns are Stewart and Lloyds from the 1950s; shame they're gone. Similar to what Birmingham used to use.
Croydon was bristling with them until a couple of years ago. The PFI is getting through them like nobody's business now.
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Re: Lighting one side of a dual carriageway

Post by Beardy5632 »

The A472 in Pontypool is a good example.
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Re: Lighting one side of a dual carriageway

Post by Johnathan404 »

I wrote:Have never seen this design though.
Except on the A32, I have seen it.
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Re: Lighting one side of a dual carriageway

Post by darkcape »

Passing through the A1 at Elkesley last week and the northbound carriageway through the new junction is lit from single columns in the central reservation, whilst the southbound is lit from columns on the verge, which I found an odd arrangement.
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Re: Lighting one side of a dual carriageway

Post by Johnathan404 »

I would suggest that's because of the bends. The outside of a bend is longer than the inside of a bend so more lighting is required on that side, whereas on a straight road you can light from any side.

Although last time I used that part of the A1 it seemed pretty messy anyway, so messy lighting would fit in.
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