[Tagging] Question about waterway=pressurized

[François Lacombe]

Hi Volker

>From my understanding, both siphon and inverted-siphon are pressurised.
Siphon uses suction to pull water downstream which implies a positive
pressure in its middle, without air.

This is an interesting concept we could classify with additional tags
dedicated to siphons.
Some pumps use this principle to raise level of a liquid (see
pump_mechanism=siphon https://wiki.openstreetmap.org/wiki/Key:pump_mechanism
)

Do you have real example of working siphon please?
I only seen inverted siphons (mainly for sewage under roads or rivers) in
the past.
This is the bottom of an inverted siphon (maybe 3m in diameter) to make
water cross a valley https://www.openstreetmap.org/way/405871631

All the best

François

Le mar. 14 sept. 2021 à 17:12, Volker Schmidt <voschix at gmail.com> a écrit :

> Question to François: is an inverted-siphon (botte sifone, pont-siphon)
> piece of waterway to be mapped as pressurised?
>
> On Tue, 14 Sep 2021, 16:18 François Lacombe, <fl.infosreseaux at gmail.com>
> wrote:
>
>> Hi Kyle,
>>
>> Le mar. 14 sept. 2021 à 03:24, Kyle Hensel <K.y.l.e at outlook.co.nz> a
>> écrit :
>>
>>>  Is there are reason why waterway=pressurized is used instead of
>>> waterway=river/stream/canal/drain and pressurized=yes?
>>>
>>
>> Yes, waterways are defined according to their permanent flowing regime.
>> Some are free flowing, others are pipe flowing.
>> A given waterway can't be both as it requires a special prerequisites to
>> handle pressurised water.
>>
>> https://wiki.openstreetmap.org/wiki/Waterways#Artificial_waterways:_pressurised_vs_Open-flow_Waterways
>>
>> This table gives all values according to their regime
>> https://wiki.openstreetmap.org/wiki/Key:waterway#Values
>>
>> River, streams, canals and drains are defined as free flowing waterways,
>> so it wasn't consistent to propose pressurised=yes for them.
>> If a river goes punctually in a permanent pressurised culvert,
>> waterway=pressurised + tunnel=culvert sounds the most appropriate
>> possibility.
>> By the way, a river relation can obviously involve sections with
>> different regimes.
>>
>> In a perfect world we would have cleared waterway=* from all other values
>> than flowing regime (move waterway=pier or waterway=fuel to man_made or
>> amenity).
>> Never mind, I go back sleeping :)
>>
>> All the best
>>
>> François
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