In this roundabout design, arrows(?) point against the flow of traffic (traffic flows along on the right side of the road).

You can particularly see it in the second image.

They indicate that you have to look out / ahead, like a yield sign. (A stopping line, but where you don't stop unless there is a need)

So they implicitly indicate that attention in needed as you progress. My first thought when seeing them, from a UX standpoint, was that they would indicated motion in a direction (it's an arrow).

Yet, that would not indicate flow in the correct direction. Then, the small arrowheads 'without serifs' did not support the idea that users would only read them as directional indicators. Then there is the grouping of them in the lane..

The reality, that they indicated a kind of flow against the direction of traffic, could still remain present in how they are 'non-standard' arrows.

Can anyone give a clear description of the mechanism by which these have their implicit meaning?

enter image description here the second image

  • I am struggling to decide the best answer to choose. The design does not appear to have origin in any implicit meaning via the perceptual system. Yet, there is a possibility for an unintended implicit meaning. – New Alexandria Jul 27 '15 at 16:10

The "shark-tooth" yield lines are not arrows that point you in a direction. They are a line of yield signs - also known as a yield line. In Europe this is a standard and all drivers are familiar with this.

enter image description here

At roundabouts these yield lines are often used in combination with a roundabout sign. The roundabout sign uses arrows to indicate in wich direction the traffic flows:

enter image description here

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    They may be a standard in Continental Europe - but they aren't used in the UK (which generally does things differently from the rest of Europe). – PhillipW Jun 19 '15 at 8:01
  • Not used in India too. Good to see this symbol. @J.T.Houtenbos I didnt understand what do you exactly mean when you say it doesnt show the direction but direction of flow of traffick. – pzv Jun 19 '15 at 9:31
  • That's what they are, but you are not addressing how they work – New Alexandria Jun 20 '15 at 22:28
  • @NewAlexandria what in "line of yield signs" doesn't address how they work? what they are is how they work! is it not or otherwise comprehended than a point of yielding that prevents drivers from having accidents with pedestrians and other vehicles? how they work is implied to be through an instruction booklet that drivers are tested upon in order to receive their licenses, in Europe. Please mark this as the best and one true answer to your question before a great many cars are destroyed! – Jedi Commymullah Jun 23 '15 at 23:57
  • @JediCommymullah read the rest of the comments, inherent meaning (arising from a natural affordance that was translated into a design), is quite different from assumed meaning. Maybe you can think of it as 'denote' vs. 'connote.' DaveAlger is the only one to address that a yield-sign is an arrow that points at you, counter to your direction of flow/travel. Please consider how I used the term "perceptual", and my answer to other discussion. best – New Alexandria Jun 24 '15 at 3:19

Here is what goes through my mind when I see those shark teeth on the road...

Am I going the wrong way? Is this against the flow of traffic? Will those things pop my tires?

In any case, driving into arrows that are pointing at you is jarring and can make you think twice and proceed with caution.

That is exactly the goal here to make drivers more alert so they don't mindlessly run into a person or a car...

enter image description here

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    "driving into arrows that are pointing at you is jarring" I think this is the key point - the wider edges of the triangles define a 'virtual line' (A bit like the gestalt patterns - what is there defines something which isn't there - redoubtreporter.files.wordpress.com/2010/06/… ) So these work not by being learnt signs but by working directly with the way we interact with the world. – PhillipW Jun 19 '15 at 8:04
  • I also like the comment by @Rolf ツ, about it resembling a row of teeth. That kind of subconscious morphology is over very important in perception & reaction. – New Alexandria Jun 20 '15 at 22:27

Sometimes bad design is just what it seems

The triangular yield indicators here are called yield lines (see Wikipedia, DOT specifications and this article on when and how they can be used) and their appearance in a single-car lane is probably the result of bad design.

They are intended to mark a position on the road where drivers should yield to other traffic (e.g. pedestrian or other vehicles). For example, the US Department of Transportation specifies:

If used, yield lines shall consist of a row of solid white isosceles triangles pointing toward approaching vehicles extending across approach lanes to indicate the point at which the yield is intended or required to be made.

In theory, the inverted triangles for the yield line are meant to mimic the traffic yield sign:

enter image description here

...unfortunately yield lines are too cryptic to be understandable to many drivers, that is, they communicate their intent very poorly.

  • Note that any interface is eventually learnable, but "drivers have become used to this crappy design" doesn't change the fact that the design is crappy to begin with.

A better approach

...would be to place a clear, large marker in the lane:

enter image description here

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    I don't agree on this. In the Netherlands and almost every other country in Europe these signs are very normal and every driver or bicyclist understands them. I don't think it is bad design. Because who would want to pass into a sharks mouth? – Rolf ツ Jun 19 '15 at 7:45
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    Also see DaveAlger's answer. – Rolf ツ Jun 19 '15 at 7:48
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    @Rolfツ As i noted in the answer, familiarity is not the same as good design. Everyone on a military base might know they shouldn't press a self-destruct button that is large, green and unlabeled, but the fact that it's green and unlabeled makes it bad design even if everyone on that base understands that it's mortally dangerous. The unlabelled, repeated sharktooth is not good design no matter how familiar it is to drivers from that locale. – tohster Jun 19 '15 at 8:00
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    @Rolfツ sorry that is just not correct. The sharktooth in this case does not mean slow down. The row of triangles is called a yield line (see this link or this link) and it means "yield to other traffic" (pedestrian or vehicle). The fact that you do not know what it means is not surprising (i.e. it's not a bad reflection on you at all), since the markings are in fact quite uncommunicative. – tohster Jun 19 '15 at 8:17
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    That's correct, and I know what it means (got my driver license here in the Netherlands). But my point is still valid: What do you first do when you need to yield to other trafic. You need to slow down. You need to look for traffic and because of that you slow down. Then you decide if its safe to cross, if not you wait (yield) for the other traffic. But I may be a little bit prejudiced because I live in the Netherlands. – Rolf ツ Jun 19 '15 at 8:29

It's a cultural difference for a stop sign, in Europe and many countries in Asia and South America (and for what I saw, some parts of Noth America), it's a clear reference and everybody knows what it means.

From a significance meaning, it's supposed to be a path that opens to give way (in Europe is popularly known as "a knife that will damage your tires" sometimes known as a Shark Teeth) and it's usually seen before a pedestrian crossing line, although it can be used in secondary roads.

This significance can be easily viewed in the sand sign version evolution, going from this:

enter image description here

to this: enter image description here

and finally this: enter image description here

Keep in mind the sign painted on the road (or lane marking) should not be used alone, but complemented with regular signs (like the ones above), light signs (flashing yellow light) or gradual messages on the lane as you approach the crossroad

If you're interested in Traffic Signs Design, take a look to this PDF about the use of Shark Teeth's on roundabouts and the MUTCD application (specifically page 35)

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    "...the sign painted on the road (or lane marking) should not be used alone..." Indeed. Some parts of the world get snow on the ground. – Ken Mohnkern Jun 19 '15 at 12:43

I believe that the implicitness comes from the assumption that you know you're on the correct lane while entering the roundabout.

Then, when exiting, the correct lane is suggested by the shape of the junction, so at that point, you shouldn't even see those signs.

  • I don't understand what mechanism underlies this implicitness – New Alexandria Jun 20 '15 at 22:29
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    @NewAlexandria I'm suggesting that the meaning of the sign is clearer if one considers its context (in this particular case, the direction from which you reach it). If the sign is taken alone, I agree that it's hard to understand. – bigstones Jun 21 '15 at 10:51
  • If it's clear then I think we must be able to state and/or deconstruct it? I'm looking for a rationale that goes deeper, or is more transparent in another direction, than that I posted in the question. Arguing that less is needed to understand... I don't think that's Teaching. No offense – New Alexandria Jun 21 '15 at 18:21
  • @NewAlexandria I'm nowhere near a teacher on the topic, so no offense taken... but I said, that to understand the sign you need to consider also the context: how is that less? Anyway, as Rolf says, it's a "learnable sign" as much as a 'serif' arrow and zebra crossings, only the last two are more widely accepted. It's a semiotic problem: the relation between sign and meaning can be totally arbitrary. You could think of them as sharktooths, but another interpretation could be that they're meant to look like stones (see also zebra crossings in Pompeii). – bigstones Jun 22 '15 at 6:32
  • anything is learnable. It become convention. For that reason, I focused the question on the perceptual mechanisms that reinforce or establish the meaning. if you are saying that there "there are none" and it's all convention... that's a viable answer. (fwiw.... I wouldn't buy it without disproof by showing the perceptual affordances of the structure are against the meaning-in-context.) – New Alexandria Jun 22 '15 at 15:19

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