[Tagging] what does maxheight=none mean?

Peter Miller peter at petereastern.com
Mon Oct 27 04:02:43 UTC 2014


I don't mind what the text is or what the tag is, but to me there is all
the difference in the world between a bridge which might be any height
(including being dangerously low) and one which definitively had no warning
sign when it was surveyed (and which can therefore be considered to provide
enough clearance for vehicles of regulation height).

For sure, people can go out with a suitable measuring device and measure
the clearance of bridges which are not signed, but this is not necessary
for 99% of routing applications and is not practical on fast roads.My
interest is to ensure that we have enough information to route tall legal
vehicles, including double-decked buses and trucks.

Without a way of tagging the fact that we know that the bridge has
regulation clearance and also knowing who surveyed it and when the data was
added we can't know what we need to do to complete the mapping to allow the
routing of high vehicles.

Personally I think the same applies to maxweight, maxwidth and a number of
other rare but important tags. I do however agree that it would not be
sensible to required every oneway tag etc etc to being tagged.


Regards,


Peter


On 27 October 2014 00:55, John F. Eldredge <john at jfeldredge.com> wrote:

> Speaking of "permanent structures", is there a recommended way of tagging
> a maxheight that is temporarily lower, such as when scaffolding is erected
> under a bridge for painting or repairs?
>
>
> On October 24, 2014 6:10:48 PM CDT, "Kytömaa Lauri" <
> lauri.kytomaa at aalto.fi> wrote:
>>
>> Personally, i use maxheight = x  + maxheight:physical=x for these, but saying that signs are the only thing that can be tagged gives bad data.
>>
>> You may not collide with a bridge, signed or unsigned. Ultrasound range finders can sometimes be purchased for under 10 euros, so without a sign there may still be a real maximum possible height for a vehicle passing under that - bridge or any other - construction.
>>
>> In most countries, "no sign" should only guarantee that a vehicle under the local legal limit can expect not to hit any permanent structures, unless they have signs. Should, but not necessarily would.
>>
>> Statements to the effect that any tags can only refer to signposted limits do not represent the original usages of the tag - only some access tags referred to legal accessibility.
>>
>> --
>> alv
>>
>> ------------------------------
>>
>> Lähettäjä: Friedrich Volkmann [bsd at volki.at]
>> Lähetetty: 25. lokakuuta 2014 0:29
>> Vastaanottaja:tagging at openstreetmap.org
>> Aihe: Re: [Tagging] what does maxheight=none mean?
>>
>> On 24.10.2014 20:53, Tom Pfeifer wrote:
>>
>>>  I stumbled over some maxheight=none tags on motorways, that did not even
>>>  pass under a bridge. I found that this is the most frequent value of
>>>  maxheight (2889 of 41474).
>>>
>> [...]
>>
>>>  For bridges without sign, there is no recommendation in the English wiki,
>>>  however the German wiki proposes maxheight=unsigned (290 uses), also used
>>>  is maxheight=default (303) and =unspecified (2).
>>>
>>>  I would recommend to add maxheight=unsigned to the English and other wiki
>>>  pages, and list maxheight=none as incorrect tagging.
>>>
>>
>> I don't like either of these
>> (maxheight=none/unsigned/default/unspecified),
>> because we should map what we see. If there is no sign, there is nothing to
>> map. Applications can make their assumptions on their own.
>>
>> Please remove the nonsensical and nonstandard maxheight=unsigned from the
>> german wiki instead of polluting other pages with it.
>>
>> --
>> Friedrich K. Volkmann       http://www.volki.at/
>> Adr.: Davidgasse 76-80/14/10, 1100 Wien, Austria
>>
>> ------------------------------
>>
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>>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
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