Safe Speed Forums

Hi All,

I was just wondering what peoples views on VAS are ?

Personally, I think in most places it is a waste of money and most sites it doesn't really help much, but I was wondering if there was any other views on them ?

In my experience, VAS installations can be either very useful, utterly useless, or can start off as one but turn into the other.

Useful: I can't recall exactly where it was, but somewhere in north London there's a stretch of road through an industrial area which feels as if it should be a 40 limit but is actually 30. Now, if you're observant, you WILL have seen the 30 signage at the start of the limit, and the streetlamps and lack of repeaters should remind you that it's still a 30, but as I said, it's the kind of road that definitely feels more like a 40. At some point into the 30 limit stretch, there's a VAS - seeing that suddenly light up as you drive towards it seems, to me, to have a far better chance of reminding you of the limit than any number of passive signs.


Useless: Whilst out on a drive through the Bucks/Oxon countryside, I find myself passing through several villages with VAS's located at the outskirts of the built-up area, within the previously posted 30 limit. Not once have I seen these VAS's ever remain blank, despite my speed never being more than 30 indicated (28-29 in reality). When you know full well that you're not speeding, it's irritating to have these things suggesting that you are.


From one to the other: There was until fairly recently a VAS sited in the 50 limit through roadworks on the M4. Initially it was quite useful, only triggering if you approached at a bit above 50. But after a couple of weeks, it turned into a useless waste of space, flashing away even if my speedo was showing between 45-50 (and according to GPS, 50 on the speedo is 47 in reality). As with the village VAS's, I don't want to be accused of speeding (even if there's no risk of being prosecuted over it) when I'm clearly not speeding.



So, when a VAS is sited in a reasonable place, and is properly calibrated and maintained such that it doesn't activate when someone is sticking to/below the limit, then I'm in favour. But if we start to see them springing up all over the place, constantly flashing away even if you're practically stationary, then they're going to lose their effect and become as much use as a few bits of black and red paint daubed on a white reflective circle...

Also, whilst I'm in favour of the signs that simply light up with a reminder of the speed limit and perhaps a "slow down" message, I'm dead against the ones which also show the speed you were actually doing - they just seem like an open invitation to all the local chavscum to try setting a new speed record.

I've just completed a literature review on road safety. This is one of the issues that arose.

It appears that VAS are more effective than cameras or signs at slowing drivers down since they target an indivdual driver.

Agreed .... all reports seem to suggest this is the case.

No profit to be gained so unlikely to be supported by camera partnerships. But I agree they are far more effective and safer than speed cameras providing they are used correctly that is.

Andy

Yes, they have to be calibrated just right. For example, there is a VAS in Willingham, about a half mile before a scamera. Of course, it goes off for everybody, but some of them are later caught by the camera. I bet they wished they had taken notice and slowed down. Trouble is, you see, that if the VAS is set even a little above exactly 30 (say 33), some people would not get VAS'd but would then go on to get a ticket.

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I stole this .sig

A VAS can be set at a speed lower then the speed limit. It has advantages therefore in being more flexible than camera in being allowed to determine an appropriate speed for certain conditions. Of course, the danger is that you may think "I haven't set the sign off - I am therefroe safe".

Thanks for the repplies.

If it's set lower than the speed limit and simply flashes "Slow Down" then it may be useful.

However, if it flashes "Speed Limit - 30" or whatever, then it's worse than useless if it's set at or below the limit. It's distinctly galling to have made the effort to drive through it within the limit and still get flashed.

Next time, some will say "why bother?"

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

If it's going off for everyone, even the drivers who KNOW they're not speeding, then naturally people are going to figure this out and start paying less attention to it... Then someone, who usually drives past this VAS at or below the limit and has now tuned out the flashing message because it's always been wrong in the past, drives past a little over the limit without realising, still tunes out the message the VAS is now correctly giving, and gets scammed. Terrific use of resources, I think not.



Not unless the camera trigger speed is so low that there's no wiggle room between the limit and the camera to place the VAS trigger speed. In a sensible installation, you'd have the camera set to trigger at 35MPH with the VAS going off at 32-33MPH - high enough not to cry wolf at the drivers who are aware of the limit, but low enough to give the just-overs a chance to ease off on the gas before the camera site.

Exactly the point I would have made if I hadn't had to leave the PC for a while... The nice thing about the VAS concept is that they don't have to just flash up the speed limit - if the reason for placing the VAS is to get drivers to slow down for, say, a sharp bend, then let the VAS flash up a message saying "Sharp bend ahead, slow down!". If there's a hidden junction, let the message reflect that.

But when the purpose of the VAS is to encourage people to slow down BELOW the legal limit due to some hazard which doesn't warrant a reduction in the limit for that stretch of road, then the VAS shouldn't simply flash up the limit to every vehicle that passes by no matter what speed they're actually doing - that doesn't educate anyone about why the VAS is there, and in crying wolf to all the drivers who are driving at/below the legal limit it makes it more likely that those drivers will ignore the next VAS they see. Let's hope that next one is also just crying wolf, and isn't trying to warn them of a genuine danger just around the corner...

DfT produce a very informative Traffic Advisory Leaflet regarding how these signs are to be deployed and what speed the trigger is to be set at.

Takes the mystery out of it all for you. I think it is 01/2003

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It's Champion Man

http://www.dft.gov.uk/stellent/groups/dft_roads/documents/page/dft_roads_508245.pdf

Thanks for pointing this out. From the Application Guidelines:

"Vehicle activated signs will not normally target all drivers but rather that population exceeding the posted speed limit or a safe speed for the particular hazard. If used correctly they will be illuminated for only a proportion of drivers and are therefore not repeater signs."

And from the Installation Guidelines section:

"Speed thresholds for warning signs should be set at the 50th percentile speed measured before installation. For speed limit signs the threshold should be set depending on road conditions. (A reasonable benchmark would be the ACPO guidelines on enforcement of 10% + 2mph; ie in a 30mph speed limit the threshold would be set at 35mph).

It is crucial that the speed monitoring detectors are installed as accurately as possible to minimise errors in speed measurement."

Which is, basically, what we've been suggesting anyway - it seems that in this case the DfT has produced a set of guidelines which are based firmly on common sense. Shame the people responsible for installing the VAS's in those Bucks/Oxon villages, or for maintaining the one in the M4 roadworks, were seemingly unaware of this document and lacking in the basic common sense that would have allowed them to install the signs without even needing to refer to the document...