[Tagging] maxspeed:type vs source:maxspeed // StreetComplete

Greg Troxel gdt at lexort.com
Wed Sep 19 12:15:41 UTC 2018

Colin Smale <colin.smale at xs4all.nl> writes:

> A "maximum" speed does not mean an "advised" speed. If you are driving
> at an unsuitable speed, below the posted maximum, in Europe you will not
> get a ticket for "speeding" as such but you may get one for "dangerous
> driving" or something similar. The obligation to drive in a safe way
> overrides all other more specific limitations. Think of overtaking -
> just because it's not prohibited, doesn't make it safe (reasonable and
> prudent). 

Mostly agreed, but in the US you can get a speeding citation in this
case.  But usually you won't.

> There is no point in trying to reflect this "reasonable and prudent"
> stuff in OSM. We should stick to the objective limits, by virtue of
> signposting and/or statutes.

Certainly I agree that trying to encode reaasonable and prudent is

>From my US driving, I would agree that encoding the actual posted or
legal limit as maxspeed is entirely satisfactory for the purpose of
communicating limits to drivers.  For routing, it's necessary to know
that sometimes typical speeds are faster, in order to get good routes
(e.g. 45 mph posted, traffic normally 65, vs another road posted 40 mph,
traffic normally 43 mph).  Needing to use a slower prudent speed for
routing happens very rarely (around me).

In the UK, I found that the default 60 mph out-of-town limit was often
faster than I considered safe, and there a lower maxspeed:practical for
routing is in order.   US-only drivers will find this surprising.

Finally, I wonder how much of this is all about streetcomplete users
being asked to input limits when there aren't signs but there are laws.
OSM's notion of verifiability has in my mind (generally, not this
discussion) been expressed too strictly; looking up the law and noting
lack of signs is entirely adequate as verification for entering limits.

Overall, I think my most useful point is that maxspeed about the law and
speeds for routing are separate issues.

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