These warning signs seem to be cropping up ever more frequently and have migrated from major roads to S2's in my area, the A456 between Woofferton and Tenbury has two sets for example. The trouble is they seem to be appearing where queues are possible (right hand turn to minor road for example) but 'likely' seems overdoing it and could breed complacency when queues are rarely seen, how about a 'queues possible' option!

Ian (M5 DRIVER)

It seems to be a policy in Norfolk to have them on approaches to rubbish dumps recycling centres, as there could conceivably be a queue when the containers are being emptied. I'm used to seeing them on busy roads, rather than on some back road with next to no traffic just because there's a tip at the end.

Tryring to follow the logic of this, I can only conclude that they are used because of the possibility of an unexpected queue, as you don't get them on the arterials into Norwich for instance, where queues are very likely!

"Queues likely for 16 miles"
The queues I see near that M3 sign are for the M25...

There's an illuminated "queues likely" sign with orange flashing lights on the A380 southbound approaching Penn Inn. It always seems to light up when there's no queue and not be lit when there is! I used to think it was incredibly silly, however I realized the reason for it fairly recently: there's no point telling you that there's a queue when you can see the queue, so it lights up when there's a (short) queue round the corner that you can't see yet.

Further on down the same road though, in Kingskerswell, there's a fairly new illuminated "queues likely" sign under a left T junction sign. I have seen plenty of queues there, but they've always been due to the usual congestion, nothing to do with that (tiny) T junction that it's talking about!

I wonder if any research has been conducted into whether or not these signs become something of a self fulfilling prophecy? I notice them on the M6 on Friday evenings when driving up to Telford, and I have noticed traffic slowing down as you would expect...Thing is, when no jam or queue appears, those people have slowed for no reason...And slowing for no reason is one of the causes of the phantom traffic jam since the braking effort has to be expelled from the system somewhere.

Does anyone actually slow down when seeing "queues likely"? Isn't it like preparing yourself for a risk of ice?

Or do you mean "queue ahead"?

No, we're talking about this permanent warning sign, not VMS messages:



I'm sure I've seen one recently in a somewhat unlikely location but can't remember exactly where.

Ah I see. I apologise.

I appreciate this isn't in relation to the OP, but the self-fulfilling prophecy is supposed to be the other way round (probably should be called something like a self-cancelling prophecy).

If you have a phantom jam, it reduces the road capacity (typically by about 1/3) and the jam exists (and moves backwards) for as long as there are more vehicles entering the jam than can be released from the jam.

If you can create a gap in the traffic so that there is even just 10 or 15 seconds where the rate of rate of entry of vehicles is less than the capacity of the jam, then the jam will simply disappear. The trick is to try and create that gap without creating a jam in the process. This is most effectively done with gantry signals that can be seen from a distance rather than reacting to the brake lights of the vehicle in front of you.