[Tagging] Feature Proposal - RFC - Roundabout Priority

Simone Saviolo simone.saviolo at gmail.com
Tue Sep 28 14:36:45 BST 2010


2010/9/28 Colin Smale <colin.smale at xs4all.nl>:
> If you leave it at that, a navigation program might not recognise it as a
> {roundabout|traffic_circle} so instead of saying "at the next roundabout
> take the second exit" it would produce confusing instructions.

Another non-problem.
> As you
> enter the "roundabout" you pass a side road entering from the left - no
> guidance here. Then you meet a side road leaving to your right...it might
> say "keep left". Then you have to give way to a road coming from the right
> - technically you could say that you are turning left onto that road so it
> might say "turn left".

Till here nothing wrong. When I'm going down a road and a second road
crosses from the left (or from the right, doesn't matter, with a give
way sign) I don't expect any hint from the navigator. You may object
that a possible "turn left" indication may confuse a driver, but then
again people are not racing rallies all the time*, so they can well
look at the road and recognize there's a wall or a monument on their
left. As to the road coming from the right, it's easy: there should be
a give way or a stop sign, or a semaphore, and the navigator should
point that out.

* Shameless plug: a new WRC game is coming out in a couple of weeks :-)

> Then you get to the exit you want and it might say
> "keep right" or maybe "straight on" or maybe nothing.

There should *not* be this problem. If the circular road is modeled as
a single way, then any node that is common to another highway=* way
should be considered by the navigator as a junction.

This is also why we would need give-way or stop or sempahore nodes on
the circular way, because otherwise it's a regular "T" junction where
the navigator *may* assume a default right-hand right of way.

> I am not an expert
> in this so I might be wrong, but it only seems fair to give the navigation
> system a hint so it can produce instructions that the driver would
> recognise in the context of the road situation. How would a satnav
> application behave if all the "junction=roundabout" tags were removed?
> Even if it's a "priority to the right" roundabout, instructions like "at
> the next roundabout take the second exit" would probably not give rise to
> many complaints that "it's not a roundabout, why are you saying that it
> is?"

It may happen that you hear the navigator tell you about a roundabout
to enter, and so you assume that you probably missed the sign because
it was hidden by a tree and enter fiercely waving an apparent right of
way that you don't have.

> After all, satnav users are frequently reminded they should keep
> their eyes open and obey the traffic rules, so no satnav will ever say
> "give way" or "you have priority".

No information is waaaaay better than wrong information. If a satnav
gives me a batch of complicated instructions I'll take a quick look at
the map (this is why the route is usually drawn with high contrast)
and learn the general direction I should go forward. If a satnav tells
me "third exit of the roundabout" I'll assume it's a roundabout; even
if I take the time to look for street signs, I will need to decide
whether the satnav is wrong. Slow down in the middle of Piazzale
Loreto in Milan to decide if you have the right of way as the satnav
tells you, and you'll win yourself a pat in the rear from the
following driver :-)

Ciao,

Simone



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