Those motorway LED sign thingys

Dr Lobster*
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Joined: Sat 30 Aug, 2003 20.14

Image

yep, you know the things. does anybody know any technical details as to how/where they are controlled from and generally how they work? are they all individually controllable or do they have to be done in sets?

i've done a lot of driving recently (not far shy of a 1000 miles) so i've seen a fair few of them and was just curious!
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m-in-m
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Location: West Suffolk/Cambs

I don't know much about them but understand that they are all connected via a private Highways Agency network. They are currently installing lots of the signs along the A14 and the cabling is run along a purple tubing.

I have certainly passed through series of them with different signs. I would imagine that they have the ability to display the same message across a series of them, or just as easily a separate message.
Jovis
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Joined: Fri 25 Aug, 2006 20.08

http://en.wikipedia.org/wiki/Variable_message_sign

^ Don't have time to read that atm, so don't know how relevant it is!
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marksi
Posts: 1892
Joined: Wed 07 Jan, 2004 05.38
Location: Donaghadee

http://www.sabre-roads.org.uk/forum/index.php

Geekery for roads/signs/lights. There's bound to be stuff on those signs in there...

EDIT: indeed there is...
http://www.sabre-roads.org.uk/forum/vie ... ns#p451608
woah
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Joined: Sun 28 Mar, 2010 12.39

They've installed some of these things on the dual carriageways near where I live, and for the past few weeks they've just been displaying 'SIGN UNDER TEST', but now they're showing 'NEW SCHOOL YEAR 01 SEP - ALLOW EXTRA JOURNEY TIME' or something to that effect.

But hardly anyone uses these roads to get to school, and it would only really have an effect in the mornings. :?: Bizarre.
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marksi
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You've had a bad week, Mark, I can tell. It's Friday. Relax. Have a pint. :)
Alexia
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Is it time for me to come out as a Sabristo?
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marksi
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Well that's at least three of us then Alexia.
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Col
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Contact:

I'm the third/fourth one...
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m-in-m
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Location: West Suffolk/Cambs

nodnirG kraM wrote:I often wonder who is in control of these signs. The M25 in particular enjoys giving misinformation on its VMSs. Whether it be QUEUE CAUTION accompanied by flashing 50 advisory limits when there is barely any traffic let alone queues; DEBRIS IN CARRIAGEWAY when there is none; or maybe the obligitory FOG on the clearest day you could imagine, generally I tend to disbelieve any message I see on that road.

Is someone sitting in a control room somewhere, bored, trying to entertain themselves? Or are they automated when there's a certain traffice volume? I know the Variable Speed Limits and Ramp Metering are semi-automatic when traffic builds up, but on non variable sections, does someone get to decide when QUEUE AFTER NEXT JCTN is used?

Is this a question for SABRE? Becuase I can't remember my password.

Oh yeah, and do they just get to choose from a list of prescribed messages, or can they be creative? Could a message say "YOU'D BE QUICKER WALKING" for example? If that were my job, I'd feel it necessary to put jokes up in a queue. You know, the first sign says KNOCK KNOCK, the next one says WHO'S THERE? etc. Or perhaps I could at least put up the reason I've been sitting in a queue for four hours. QUEUE AHEAD is of little use when I'm already in it. Why can't it read QUEUE AHEAD BECAUSE SOME DICK IN A BMW WAS CHATTING ON HIS PHONE WHILST ADJUSTING HIS UNDERWEAR WITH THE OTHER HAND AND THEN SPILT COFFEE ON HIS LAP BECAUSE HE'S JUST THAT MUCH OF A DICK. HE'S OKAY BY THE WAY, JUST MINOR INJURIES. SERVES HIM RIGHT I SUPPOSE. DICK.
From what I have read the M25 signs work on the basis of slowing traffic down to avoid causing a bottleneck. So they detect the level of traffic is above a threshold and reduce the speed limit in the immediate area to 40mph (the lowest the system is allowed to do), 50mph further out and 60mph further from that. From what I read if the system works well it actually avoids you actually coming to a standstill.

The entire system appears to be automated without needing intervention.
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BBC LDN
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Location: Richmond-upon-Thames

I knew I recognised that image from somewhere...

Image

For reasons passing understanding, I've had that image on my computer for five years - I must have been unknowingly saving it for today. That's destiny, that is.

...or perhaps an indication that I need to clean up a lot of the shit on my hard drive.
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