[Tagging] length=

[moltonel 3x Combo]

On 27/01/2015, Mike Thompson <miketho16 at gmail.com> wrote:
>> The way in OSM is only a (sometimes not precise) drawing of an existing
>> feature and can be different from the reality.
>
> How precise is the value of the "length" tag? From what is the value
> derived?

In my experience of hiking trails in Ireland, the length advertised
on-site and in leaflets is often 10-20% off (as measured by my treking
GPS that takes relief into account). I expect OSM + SRTM to be more
precise. YMMV of course.