[Tagging] How to tag a narrow cul de sac without turning possibility

Volker Schmidt voschix at gmail.com
Tue Mar 23 21:27:38 UTC 2021

The width=* does not help (even though I normally tag it anyway). The
essential feature of these roads is the absence of highway=turning_circle
and turning_loop, and also of the possibility of a three-point-turn
<https://en.wikipedia.org/wiki/Three-point_turn> for anything of the size
of a  normal car and upwards.
I could put a width=* on the last node of the way, but that breaks all
kinds of conventions.

The noexit=yes is not suitable as it is only intended for mappers. In
addition it only says this road leads to nowhere, but it does not say that
there is no road widening for turning.

The bicycle or motorcycle turning issue I left out for simplicity. Also if
you have a Smart-sized car you may be able to turn around.

Looking at it from the functional point of view, i.e. how can a
bicycle/car/hgv router decide if I need to leave the road in reverse.
It needs to know the width of the road and the fact that is non widened at
the dead end.
Hence two tags: width=* on the way, and highway=not_widened, or
not-widened=yes, on the end node.

On Tue, 23 Mar 2021 at 19:29, Mateusz Konieczny via Tagging <
tagging at openstreetmap.org> wrote:

> Mar 23, 2021, 19:15 by baloo at ursamundi.org:
> On Tue, Mar 23, 2021 at 12:48 PM Volker Schmidt <voschix at gmail.com> wrote:
> I have come across many single lane residential roads where a normal car
> cannot turn around,
> Example 1 <https://www.mapillary.com/map/im/y4NQen772DtrUKkP6HRpyw>
> Example 2 <https://www.mapillary.com/map/im/lTqcaKaU5U5g4-zF6jVByg>
> Example 3 <https://www.mapillary.com/map/im/hObPDg7REcn8v2cfXOwjbg>
> Is there already an established tagging to indicate that there is no
> turning possibility.- This would be useful to prevent mainly delivery vans
> and similar from ending up there and having difficulties getting out again.
> Something like
> lanes=1
> oneway=no
> uturn=no
> No lanes are marked or implicit, so don't tag lanes=* at all.
> Mapping lane count is fine in cases without marked lanes where
> lane count is obvious and clear.
> One can add also lane_markings=no
> https://wiki.openstreetmap.org/wiki/Key:lane_markings
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