Here is a few bullet point explaining my reasoning to decide if it is a
tunnel or not :
- I think that most of the exceptions mentioned, are well-known as being
a tunnel (like tunnel in Brussels). Thus it is not a problem for these.
- If you have nothing on top, and it is a passage going under something,
it is always a tunnel (like below a city, below a mountain, ...). if you
don't have something directly on top (no road, no railway...), there is no
question to me. Even if you generally have roads/railways somewhere above
these type of tunnel (For example, you often have something on the
mountain, but it is not "directly on top").
- Thus, the question is only posed in case where two
railway/highways/rivers/... (or any combination of them) crosses each
others. Then the usual rule of thumb can be applied :
1. if it looks like a bridge = a bridge;
2. if it looks like a tunnel (longer than wide, structure looks like
one, ... -> WHATEVER is your definition, it will always be subjective) then
it is a tunnel, ...
And we probably will always disagree on some of these interpretation. The
only case where it is really verifiable is when there is a sign telling
"bridge n°4295" like on our motorways or if the structure is named ("Viaduc
Herman Debroux", "Tunnel Montgommery", ...) or if an official database
exist with a classification.
Le mer. 29 mai 2019 à 06:04, Marc Gemis <marc.ge...@gmail.com> a écrit :
> additional things that can be part of the definition:
> - passages through embankments are (in general) not tunnels.
> - when a road passes over another one, located in a cutting, does not
> place the lower one in a tunnel (Antwerp ring road)
> - when the road goes under a waterway, the road is in a tunnel
>
> Again: exceptions will exist and they have to be seen as a rule of
> thumb, not a hard definition.
>
> On Wed, May 29, 2019 at 5:46 AM Marc Gemis <marc.ge...@gmail.com> wrote:
> >
> > AFAIK the tunnel=building_passage, this is not a tunnel, but using the
> > tunnel tag anyway. I guess the same is true for culvert. I would not
> > try to come up with a definition that is also applicable to those 2.
> >
> > Maybe my rule of thumb could be extended somehow for the metrotunnels,
> > which are clearly underground, and are therefore tunnels. For the mole
> > pipes, you write "dug out and covered", which is another indication
> > that it is a tunnel.
> >
> > That being said, I guess you will never find a definition that works
> > 100% of the time, because the real world is just messy.
> >
> > On Tue, May 28, 2019 at 11:57 PM Stijn Rombauts via Talk-be
> > <talk-be@openstreetmap.org> wrote:
> > >
> > > Hi,
> > >
> > > First: the interpretations given here to 'tunnel' are much more strict
> than the wiki, which leaves much more room for interpretation. A strict
> interpretation of tunnel makes the use of tunnel=yes of tunnel=culvert for
> passages of rivers underneath a road senseless, just as
> tunnel=building_passage.
> > >
> > > Second, I hope that you are aware of the consequences of your
> interpretations. Let's use the definition of Marc, which is the most
> elaborated: "I apply the rule: stand on the road, look up, which layers of
> material do you "see" before you reach the sky? Is there earth
> (grond/aarde) that was not placed there artificially, then you are in a
> tunnel.": Then the 'railroad tunnel' between Brussels North and Brussels
> South is NOT a tunnel. It is just a mole pipe (in the words of Gerard). The
> whole thing is dug out, built and then covered with streets, buildings and
> here there a bit of gorund.
> > > Even a lot of the metrotunnels are made with the 'cut and cover'
> technique and are thus NO tunnels? Ecoduct Kikbeekbron over the E314 is NOT
> a tunnel?
> > > Also the examples given by Marc and Tim with such a thin cover are
> most likely made 'cut and cover' and have only 'artificial' things
> overneath: NO tunnels...
> > > And what do you do with the GEN-constructions at railway 161 in
> Genval? The railway has been covered with roads and parking lots. Also no
> tunnels?
> > > On the other hand: ecoduct Groenendaal really looks like a bridge but
> has been mapped as a tunnel...
> > >
> > > Lionel said : "A tunnel is generally something that was dig (removing
> earth/material) and consolidated from the inside (most often with concrete)
> like a subway tunnel if you want. It seems pretty rare to dig a big hole,
> make a tunnel and put back the earth on top !": Yet, that ís a very common
> practice...
> > >
> > > So to me these seem to be useless definitions...
> > >
> > > Or does the word 'artificial' means that ground level matters? The
> ringway around Antwerp (R1) is almost everywhere at level -1, below ground
> level. The cutting is here the artificial structure (using Yves' words this
> time). So where there is a road going overneath, the ringway goes through a
> tunnel...? The same for Joost's example: if you look at the aerial imagery,
> you can see clearly they had to dig out the N28 to get underneath the
> railway and the other roads: thus a tunnel...? And what about the complex
> traffic changers where it is often very hard to see what the original
> ground level was.
> > >
> > > @ Yves: 'Layer' gives a relative position. Something at ground level
> can perfectly have layer=-1 or layer=1. Check the wiki. And further: a
> bridge with layer = 1 doesn't mean it is above ground level; a tunnel with
> layer = -1 doesn't mean it is below ground level.
> > >
> > > @ Tim: What came first is a useless criterion. The E313 was
> constructed before the E314, but it is definitely a bridge of the E313
> above the E314. And the definitions of bridge or a tunnel should be so that
> anyone knows whether to map things as bridge or tunnel without having to
> know in which order roads, railways, etc. were constructed.
> > >
> > > So can someone can come up with a useful definition?
> > >
> > > Can I come up with a definition? I like the length/width ratio, the
> open bridge(like) structure against a confined tunnel(like) structure. And
> the fuzziness of the wiki. But one thing is very clear for me: ground level
> doesn't matter.
> > >
> > > Regards,
> > >
> > > StijnRR
> > >
> > >
> > >
> > > Op dinsdag 28 mei 2019 18:52:50 CEST schreef Marc Gemis <
> marc.ge...@gmail.com>:
> > >
> > >
> > > This is the place:
> > >
> https://www.google.com/maps/@51.2216551,4.0345363,3a,75y,49.39h,77.96t/data=!3m6!1e1!3m4!1sjggCIzrpgLhVFtrn6gYCnQ!2e0!7i13312!8i6656
> > > (sorry no Mapillary images yet).
> > >
> > > Burchtakker (the parallel road) is lowered near the (bicycle) tunnel
> > > under the E34/A11.
> > >
> > > On Tue, May 28, 2019 at 6:36 PM Marc Gemis <marc.ge...@gmail.com>
> wrote:
> > > >
> > > > I think there is a tunnel under the e34 between Antwerpen en
> Zelzate. There used to be a level crossing which was removed and instead
> they created an underground passage for it.
> > > >
> > > > M
> > > >
> > > > Op di 28 mei 2019 14:46 schreef Lionel Giard <lionel.gi...@gmail.com
> >:
> > > >>
> > > >> @joost schouppe To me that's indeed a bridge, as you see the same
> structure as on the motorway bridges : a platform supported by pillars....
> > > >>
> > > >> A tunnel is generally something that was dig (removing
> earth/material) and consolidated from the inside (most often with concrete)
> like a subway tunnel if you want. It seems pretty rare to dig a big hole,
> make a tunnel and put back the earth on top ! ;-)
> > > >>
> > > >> I can't find example of tunnels that's really like "under a railway
> or motorway", so i would say that probably 99% of the tunnel are below
> ground or mountains/hills (if we exclude the obvious building passage that
> we classify as tunnel in OSM). They are generally longer than wide as
> someone quoted from wikipedia.
> > > >>
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