A discussion in a thread on Wirral waters threw up the subject of street light. It seems Wirral council is intending to replace inefficient street lights with LED units which, being more efficient, will save money and allow them to abandon their plan of switching the old ones off at night.

http://communityactionwirral.org.uk/wirrals-new-street-lighting-strategy-launched/

I am all for this, and these new lamps are evidently 'smart' in that they can be controlled from a central point and dimmed if necessary so over-illumination doesn't occur. It will save a great deal of money and save a lot of electricity and maintenance.

But I wonder if the council has realised that LED lamps - unlike the old sodium lamps they are replacing - can be switched on and off in nanoseconds rather than minutes. This makes it perfectly feasible to use PIR detectors to switch them on only when someone is present. This means that in many suburban roads which are largely deserted for much of the night the lights could quite easily be left in darkness until someone comes along, thereby saving even more money.

It also has the advantage of saving a great deal of light pollution which currently completely covers cities and towns with a vile orange luminous smog. Most people living there would rather like to see the stars.

That's an interesting idea about the sensors, and I agree totally about the light pollution. However, I wonder if intermittent traffic might create a sort of flickering trail of light effect that might be distracting not only to road users but people living nearby? Not so bad if they were used only through the quiet late night hours, I guess - then we could go star-gazing! As long as we stayed very still...

They could save even more money by cutting the ivy and the tree's blocking the lights and leaving them on all day, I see the light that has been on permanently for at least three years on the Barnston road has now been sorted unless the bulb itself has finally given up, saving money has never been top of this council's list, seems government cuts has really started to bite where it really should bite,cutting Councillors and their expenses.

I take your point about flickering, but if you had a 1 minute (say) on period after the last trigger, they would stay on rather than flickering. These are 'smart' lights remember, and my bet is that there is a microprocessor associated with each one.

Adding facilities like learning traffic patterns or distinguishing between people and cars or dimming the light slowly rather than abruptly switching it off is something that would be dirt cheap to add.

You might have a system which adjusts background light continuously according to the traffic pattern over ten minutes, brightening the light when traffic is heavy and allowing it to get dimmer as the traffic diminishes for instance. You might even give people or cars transponders to tell the lights near them to come on etc.

There are lots of fascinating possibilities.

They can't do it quickly enough. I hate the horrible orange light pollution especially as it plauges my night photography. The tunnel approach road has been led lit for a while now. Its much easier on the eyes at night and no light is wasted shining in the sky.
In work I have just replaced a load of old 400w metal halide fittings in a large hall with 150w led floods. The energy savings are huge.

I'd like to replace the lights in my house with them, but they are too expensive and not bright enough.

The brightest replacement I've found was on sale in ASDA which produced 1,500 lumens; about what you'd have got from a 100W incandescent All the other's I've seen manage about 800, which is what you'd get from a 60W incandescent.

Unfortunately I didn't snap up the ones I saw in ASDA. £15 for a lightbulb is too damn expensive. I will wait until they get cheaper.

I came across an announcement by Messrs Cree who are a leading manufacturer of LEDs. They have developed a single-chip LED capable to producing 2,500 lumens. This I think is a game changer. When it hits the market we shall see remarkable things I think.

http://www.cree.com/News-and-Events/Cree-News/Press-Releases/2014/December/XHP-LED-release

You make a fair point Excoriator but don't just base it on lumens. It has more to do with visible light. Most ordinary old style, and some new, give out a yellowish light and so needs a greater output for the human eye to use it. The newer LED lights work on a much whiter light making more of the visible spectrum available and so needing lower wattage/lumens and why they are more cost effective.

The miserable attempts at using LED lighting in Woodchurch Lane, Birkenhead is certainly not a good sales point, mid-way between lights it is near pitch darkness.

Other places on Wirral with LED street lamps have seemed a lot better.

Great to see cree making so much progress on efficiency, 70% (150 lumens per watt) is very impressive. A 2500 lumen lamp would only need 16 watts, combine that with a (say) 90% efficient switching regulator and you'd end up about 18 watts needed.

I've used compact fluorescents since they came out (initially at about £40 each), well over half of them don't last more than about three years, lets hope the reliability of LED lamps is somewhat better.

The council have replaced some of the triple "retro-antique-style" lamps on New Brighton prom with LED lights. The original triple fittings were relatively new (10 years old?) but seemed unable to cope with the weather judging by the number that failed or simply fell off. They have been replaced with a single LED lamp, and the brackets for the other two lamps cut off (!)

The end result, however, looks rather odd. A very tall pole with a little farty single LED fitting at the top. I never understood why those poles had to be so tall in the first place, now they just look silly.

I'm not familiar with what's been done in Woodchurch lane but I suppose if you put dimmer lights on posts that are too far apart, you will have a poor solution. I guess they don't want the expense of changing the lamp-posts and have cut corners on the lamps too.

As to CFLs, When they were expensive, I wrote the shop I'd bought them from and the date when I plugged them on the base somewhere, and if they failed early (many did) I took them back and got a replacement. Nobody ever quibbled. They are much cheaper now so I don't bother, but I don't find them much more reliable.

Leds slowly lose output with time too, so they are not perfect either. I guess, like old soldiers, they won't die, but will simply fade away...

This effect happens faster if they run hot, and keeping them cool seems to account for most of the bulbs and fittings' bulk. Look at the heatsinks on these for instance! http://www.amazon.com/Newsun-Bright-Headlight-Philips-Hi-low/dp/B00R7BLFD6 Some are even fan cooled! I guess if they ever crack this problem, they will become a lot more compact and easier to use.

I can't wait to see the end of the vile orange sodium lamps. The sooner the better and hang the expense!

I made a diversion down Woodchurch Lane this evening, and see what you mean, diggingdeeper! The lighting there is totally inadequate.

Lets hope they take this as an example of what NOT to do elsewhere, rather than a model for the rest of the borough, or we shall all have to carry torches.

Speaking of which, I bought a chinese single LED torch on Aliexpress about six months back. I think it cost about a tenner, came with a lithium ion battery and charger and is the best hand torch I've ever owned. It claims to be 1,800 lumens, but in fact I think that's exaggeration. Its more like 800, but it compares with car headlights despite being only about 6""long and 3/4" in diameter.

Anyone seen any sign of these new lights being installed yet?

Still got the horrible yellow ones round here.

The first roll-out is supposed to be somewhere around the Woodlands Primary School area.