Double negative signs

[Having a cuppa]

So a circular sign with a red roundel indicates a prohibition. For instance if there is a pictogram of a pedestrian inside the red roundel, that indicates pedestrians are not allowed beyond that point. There is a road sign with the words "no articulated vehicles" inside the red roundel. https://assets.publishing.service.gov.u ... -signs.pdf Pg 17 Isn't this technically a double negative?

[Bryn666]

So a circular sign with a red roundel indicates a prohibition. For instance if there is a pictogram of a pedestrian inside the red roundel, that indicates pedestrians are not allowed beyond that point. There is a road sign with the words "no articulated vehicles" inside the red roundel. https://assets.publishing.service.gov.u ... -signs.pdf Pg 17 Isn't this technically a double negative?

It is technically, but if it just said "articulated vehicles" people would argue it isn't clear. Remember that signing is never perfect, there'll always be an outlier that causes an issue.

[Chris584]

I would have thought a sign with no symbol but with a supplementary plate with the wording on would be correct if no articulated vehicle symbol is available.
Red circles with symbols in would benefit a diagonal red stripe as with no right turn etc. That would make it crystal clear that the symbol representing pedestrians or certain vehicles were not allowed.

[nowster]

Sometimes you apparently need the stripe. https://goo.gl/maps/jzT4fYuob9pcTSTW6

[Having a cuppa]

I would have thought a sign with no symbol but with a supplementary plate with the wording on would be correct if no articulated vehicle symbol is available.
Red circles with symbols in would benefit a diagonal red stripe as with no right turn etc. That would make it crystal clear that the symbol representing pedestrians or certain vehicles were not allowed.

States with Worboys-style signage, such as the Republic of Ireland and Hong Kong and to a lesser extent Iceland, have modified the traditional red roundel to feature a diagonal red stripe. It makes much more sense for the average person as the red roundel with the diagonal stripe is the international symbol for "no", but sign purists would argue for people to learn the meaning of the signs and the meaning of the design, even if it varies from what makes sense.

[A303Chris]

Sometimes you apparently need the stripe. https://goo.gl/maps/jzT4fYuob9pcTSTW6

That is more the way it is shown on the continent and personally a red line is defiantly clearer for people to understand

[nowster]

I believe the Vienna Convention (which the Worboys signage is based on) specified the diagonal stripe.

Original meaning was:

Red ring or blue face circular sign = mandatory.
Stripe = don't do this.

[Big L]

Sometimes you apparently need the stripe. https://goo.gl/maps/jzT4fYuob9pcTSTW6

That is more the way it is shown on the continent and personally a red line is defiantly clearer for people to understand

Especially in that example because there is no requirement for pedestrians to have any knowledge of the highway code. But there is an argument for the introduction of the red diagonal to make the intention of more signs clearer.

[jervi]

Sometimes you apparently need the stripe. https://goo.gl/maps/jzT4fYuob9pcTSTW6

That is more the way it is shown on the continent and personally a red line is defiantly clearer for people to understand

Especially in that example because there is no requirement for pedestrians to have any knowledge of the highway code. But there is an argument for the introduction of the red diagonal to make the intention of more signs clearer.

Not knowing the law is never an excuse to breaking the law.
So unless you are under the age of criminal liability there is a requirement for pedestrians to understand, and even if someone is under the age of criminal liability it kinda falls on their parent/guardian to ensure they know what they can and cannot do / be there to stop them from doing something they shouldn't do.

[Stevie D]

Not knowing the law is never an excuse to breaking the law.
So unless you are under the age of criminal liability there is a requirement for pedestrians to understand, and even if someone is under the age of criminal liability it kinda falls on their parent/guardian to ensure they know what they can and cannot do / be there to stop them from doing something they shouldn't do.

All of that is true, but the law is not some abstract theory like the rules of chess ... it is there to protect the individual concerned and everyone else. If the regulation signage is unclear and is likely to be misinterpreted, putting people in danger, then the regulations should be changed so that the signage is clear and unambiguous.

[Gareth]

I would have thought a sign with no symbol but with a supplementary plate with the wording on would be correct if no articulated vehicle symbol is available.
Red circles with symbols in would benefit a diagonal red stripe as with no right turn etc. That would make it crystal clear that the symbol representing pedestrians or certain vehicles were not allowed.

States with Worboys-style signage, such as the Republic of Ireland and Hong Kong and to a lesser extent Iceland, have modified the traditional red roundel to feature a diagonal red stripe. It makes much more sense for the average person as the red roundel with the diagonal stripe is the international symbol for "no", but sign purists would argue for people to learn the meaning of the signs and the meaning of the design, even if it varies from what makes sense.

The UK signs were also planned to have the bar until fairly late. There are official drawings of them in the public domain.

Research suggests the bar offers better comprehension but with a trade-off of slightly longer reading time.

Hong Kong pretty much shows what our signs would look like with the bar.

[Bristol]

I believe the Vienna Convention (which the Worboys signage is based on) specified the diagonal stripe.

Indeed - I'm sure I've seen pictures of an old German sign book where a black arrow straight ahead on white with a red ring means you MUST go straight ahead (we'd sign that in blue today of course) but the same sign with the stripe means you MUST NOT go straight ahead (I think that was like the white bar no entry sign).

That would probably confuse a lot of drivers today, even if it makes sense.

Maybe this has something to do with why we've kept the bar on no turning left/right signs. And roads.org.uk IIRC has an article on the "no straight ahead" sign in Ireland.

[Chris584]

In the republic of Ireland they do have a sign with red circle and black arrow pointing up on a white background which confusingly, to me anyway, mean don't go straight on.

[FosseWay]

Not knowing the law is never an excuse to breaking the law.
So unless you are under the age of criminal liability there is a requirement for pedestrians to understand, and even if someone is under the age of criminal liability it kinda falls on their parent/guardian to ensure they know what they can and cannot do / be there to stop them from doing something they shouldn't do.

All of that is true, but the law is not some abstract theory like the rules of chess ... it is there to protect the individual concerned and everyone else. If the regulation signage is unclear and is likely to be misinterpreted, putting people in danger, then the regulations should be changed so that the signage is clear and unambiguous.

Exactly this. It's not a zero-sum game, where "drivers must know the meaning of road signs" makes "road signs must be as clearly understandable as practicable" irrelevant. Consider a comparison with defensive driving. You are circulating on a roundabout and therefore have priority over traffic entering the roundabout from your left. But you see someone approaching the give way line rather fast and it becomes clear that they are not going to stop. Either you carry right on and insist on your priority, thus risking a collision with the errant vehicle or losing control in your attempts to avoid it, or you slow down and let it pass unmolested. The duty of the joining vehicle to give way is not in doubt, regardless of your choice of behaviour; but your choice of behaviour has an additional direct effect on everyone's safety. I'd say the same applied with official signage - the duty of drivers to learn what signs mean is not in doubt, but the authorities' choice of signage has an additional direct effect on everyone's safety.

Personally I think the red stripe should be included in all prohibition signs. Under the current arrangement, you could in fact argue that a standard speed limit sign means something other than what we all take it to mean. A symbol in a red circle means "don't do that thing", right? In that case 30 in a red circle means "don't do 30". 29 or 31, or any other figure above or below, is fine, but don't do 30.

There are some signs that are entirely non-self-explanatory. The blue and red parking/stopping restriction roundels are two such, but they are so ubiquitous that people do in practice understand them to a basic extent ("don't park here"). But sometimes you come across signs that defy any kind of interpretation, but which are sufficiently rare not to be remembered. In Sweden you can get plates beneath the standard "other hazard" warning triangle with either five horizontal dots or three dots arranged in a triangle surrounded by a circle. These apparently mean "warning for blind people and deaf people" respectively. How those symbols mean those things beats me.

As a roads authority, you can argue till you're blue in the face that anyone driving past such signs must learn what they mean, but so long as humans are imperfect you have to accept that some, many or virtually all won't. If there is a reasonably practical way of making the sign easier to understand, your moral duty to do so is as absolute as drivers' moral duty to understand signs is.

[Gareth]

The parking/stopping signs tend to be some of the least understood internationally. Perhaps the most misunderstood one is the red circle with nothing in it, meaning "no vehicles" or "road closed" in some countries.

[Bristol]

Perhaps the most misunderstood one is the red circle with nothing in it, meaning "no vehicles" or "road closed" in some countries.

I thought that was a UK problem? In Germany and Switzerland these signs are widespread on private, forest and other tracks and no-one seems to have a problem understanding them.

I don't think I've seen one over here for ages because we have ROAD CLOSED boards, but I think there's a few around Gatwick Airport - with NO VEHICLES written underneath in case someone wonders what it means!

[SteelCamel]

Personally I think the red stripe should be included in all prohibition signs. Under the current arrangement, you could in fact argue that a standard speed limit sign means something other than what we all take it to mean. A symbol in a red circle means "don't do that thing", right? In that case 30 in a red circle means "don't do 30". 29 or 31, or any other figure above or below, is fine, but don't do 30.

It does mean that, if you think about what speed means. 30 miles per hour means you cover 30 miles in one hour. If you do 40mph, you will cover 40 miles in an hour. But if you've covered 40 miles, you must have covered 30 miles. Imagine driving at a constant speed for an hour. If you've gone 29.9 miles or less when the hour expires, you're fine, as you haven't covered 30 miles. If you reach 30 miles before the hour expires, you're in trouble - whether you go another yard or another 30 miles - because you went 30 miles. Of course speed isn't actually measured over a full hour, but that's the idea.
The same applies to the minimum speed - if the hour expires and you've only done 29 miles, you're booked, because you didn't do 30 miles. If you reach 30 miles before time expires, whether you just scrape in or go 30 miles more within the hour, you're OK.

[FosseWay]

Personally I think the red stripe should be included in all prohibition signs. Under the current arrangement, you could in fact argue that a standard speed limit sign means something other than what we all take it to mean. A symbol in a red circle means "don't do that thing", right? In that case 30 in a red circle means "don't do 30". 29 or 31, or any other figure above or below, is fine, but don't do 30.

It does mean that, if you think about what speed means. 30 miles per hour means you cover 30 miles in one hour. If you do 40mph, you will cover 40 miles in an hour. But if you've covered 40 miles, you must have covered 30 miles. Imagine driving at a constant speed for an hour. If you've gone 29.9 miles or less when the hour expires, you're fine, as you haven't covered 30 miles. If you reach 30 miles before the hour expires, you're in trouble - whether you go another yard or another 30 miles - because you went 30 miles. Of course speed isn't actually measured over a full hour, but that's the idea.
The same applies to the minimum speed - if the hour expires and you've only done 29 miles, you're booked, because you didn't do 30 miles. If you reach 30 miles before time expires, whether you just scrape in or go 30 miles more within the hour, you're OK.

I can see how you can make that kind of connection in the same tenuous way as my original comment! But actually, in that case, the sign still doesn't mean what we think it means, since a 30 in a prohibition roundel would mean it's unacceptable to do 30. 29.9 is OK, 30.0 isn't. That isn't the case - if you're doing 30 in a 30 limit, you're obeying the letter of the law.

[SteelCamel]

I can see how you can make that kind of connection in the same tenuous way as my original comment! But actually, in that case, the sign still doesn't mean what we think it means, since a 30 in a prohibition roundel would mean it's unacceptable to do 30. 29.9 is OK, 30.0 isn't. That isn't the case - if you're doing 30 in a 30 limit, you're obeying the letter of the law.

True, my extremely literal interpretation says that exactly 30mph isn't allowed, while the law says it is. But realistically it's not possible to do exactly 30mph. If you do 30.0000000001mph you're both breaking the the law and my literal sign interpretation. If you do 29.999999999mph, you're fine for both. In the real world there's no difference between "you may not do 30mph or more" and "you may not do more than 30mph". Even if you came up with a device to measure speed with infinite precision and perfect accuracy, the car isn't at absolute zero, so it's not all moving at the same speed - and for that matter neither is the detector, or the road. If the prosecution needs a quantum physicist to make their case, they will give up pretty quickly

[Sulzer:1999]

Perhaps the most misunderstood one is the red circle with nothing in it, meaning "no vehicles" or "road closed" in some countries.

I thought that was a UK problem? In Germany and Switzerland these signs are widespread on private, forest and other tracks and no-one seems to have a problem understanding them.

I don't think I've seen one over here for ages because we have ROAD CLOSED boards, but I think there's a few around Gatwick Airport - with NO VEHICLES written underneath in case someone wonders what it means!

These signs are ubiquitous in Sweden, to be seen in both urban areas and at the gates of remote forest tracks.
For some reason, these Swedish signs have an unusually thicker than normal circle.
Nearer to home, there’s a long bypassed section of the A944 west of Aberdeen just before the Lang Stracht roundabout, where at first glance there appear to be plain ‘No vehicles’ signs but are accrual ‘flying motorbike’ signs that have faded.

Murray Duncan