OT: Motorway lights one cones... in sync?

[dmc]

Off topic I know but...

Noticed this a few times before and have just driven down the M20 and seen it again.

On the motorway, all the lanes are closed and a long row of cones has been put out to put all the traffic onto the hardshoulder. Nothing odd with that, but instead of normal flashing lights they have dim yellow lights that appear to strobe every couple of seconds - in sync

They give the impression of fast moving bright lights running down the line of dimmer ones (if that makes sense)

At first I thought it was just luck and was due to the way the guy turning them on walked down the row of cones but the more I see them the more convinced I am that they are some how linked. It's just too perfect to be coincidence surely?

Anyone know how they work? I've only noticed them on the M20 - not the M2 or the M25. Testing something new mebbe?

Darren

[Andrew Gabriel]

They're Dorman Synchroguide lamps. There's a video on their webpage:

They give the impression of fast moving bright lights running down the line

Testing was some years ago. I've seen them on the M1 and M3.

[Frank Erskine]

WTF's the M20?

[geoff]

In message , Frank Erskine writes

A car park ...

[Bob Eager]

WRONG! Officially (often) it's a lorry park...

[Bob Smith]

I have seen them on the M62 near Hull. It is either a fance piece of kit, or some bloke in yellow got bored.

Bob

[Mark Carver]

On a similar topic the A12 between Chelmsford and Colchester has active cats eyes. White(ish) LEDs facing you, if you dart your eyes about they flicker, at what I estimate to be a 50% duty cycle. Presumably there's a solar cell to charge up a battery during the day, and the 50% duty extends the life of the charge. You'd need 16 hours this time of year ?

[Chris J Dixon]

wireless link?

Chris

[Brian Sharrock]

The Telegraph had an item about these 'self illuminating' cats-eye replacement units, yesterday (Thurs). Instead of glass spheres reflecting headlamps back to the driver, these devices contain illuminators (LED) themselves. It's claimed that the lamps are visible further than the reflections off a car, and that two hours of sunlight will provide ten 'days' of illumination

[TheOldFellow]

Isn't that the one people use to escape rip-off, sleaze-ridden, prat-p overregulated Britain for the wonders of Sarkozy-land and pojnts sarf?

Usually stuffed with parked Polish wagons.

R.

[Mike Harrison]

I've wondered about this ( being the sort of person who likes figuring out how things work..)

I initially though they may use an optical link, each one detecting the one behind it. However I concluded it would be hard to prevent them detecting the one further back instead/as well.

I have also occasionally seen a string with one or two flashing out of sequence, so my guess is it is a wireless link (probably 434 or 868MHz) , and each one either has a fixed number in the sequence, so they need to be put out in the right order. They would only need periodic resynchronisation, so the wireless bandwidth wouldn't be too much of a problem. Another possibility, to avoid them needing to look at the numbering every time they are deployed is that they live in a charger/holder of some sort on the lorry, which assigns numbers in sequence as each one is pulled out to put on the cone (and maybe the out-of-sequence ones I saw had been rearranged after starting).

I'd really like to know...

[Edwin Spector]

I was beginning to think that I was the only person to notice the pulsed LEDs which are becoming so common. My friends don't seem to notice it. I find the rear lights of the new VWs etc really distracting. Ditto for my car's LED instrument lights.

The pulsing is a good way to save power (as mentioned), and works because our eyes perceive the _peak_ light level, not the average.

Driving past motorway roadworks, I am aware that the 'non-flashing' yellow lights on the cones are actually pulsed too, at a duty cycle around 50%. The LED tail lights are more like 10%. I have also seen some LED traffic lights which are really horrid at night due to the pulsing.

We also have the pulsed active cats' eyes on the A46 near Bath.

Cheers

Edwin.

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[Simon Finnigan]

The ones i`ve used have an optical link - they need line of sight to work. You put them out in any order and they work. If you have one light, with 2 or more lights the same distance behind them (not good on a road, but useful when playing with the kit) ALL the lights behind the first one flash at the same time.

[Mike Harrison]

Another reason for pulsing on tail light sis so they can also be brake lights just by changing the duty cycle.

Different people have different sensitivity to this - it is also more noticeable in preipheral vision

[John Rumm]

They have them on the A39 as well IIRC... I think that is where I first noticed them.

The most distracting thing I noticed (other than the strobing) is that they illuminate on both sides when triggered by the car headlamps. So you also see a line of pulsing cats eyes in your rear view mirror - an effect you don't get with the real ones.

[Andy Dingley]

Optical. The clever thing isn't that they're linked, but that they can also sort themselves out for synchronisation. If they were purely wireless they wouldn't know which way was "forwards" and they'd be just as likely to start themselves up in reverse order.

[ARWadsworth]

Have a look at

[dmc]

uk.d-i-y once again proves it worth in answering the questions that make my wife think I'm mad ;-)

Cheers!

Darren

[Dave Liquorice]

I hate the damn things flickering away in my preipheral vision, most distracting on a dark country A road, ie not illuminated.

They bunged a stetch of the 'orrible things down the middle of thee A686 near Penrith a few years back. I'm glad to say most of them have now failed... Traditional reflective cats eyes last for donkeys years and I expect are considerably cheaper.

[Andy Champ]

Annoys the heck out of me too.

Any car manufacturers reading this might like to know that if they do that to the instrument lights I will not be buying that car.

Andy