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

Tod Fitch tod at fitchdesign.com
Wed Sep 19 06:01:32 UTC 2018

> On Sep 18, 2018, at 6:19 PM, Joseph Eisenberg <joseph.eisenberg at gmail.com> wrote:
> So on the boundary=administrative admin_level=6 for Rogers County, we could have something like maxspeed:type:default=45mph

Except that more typically there will be different default speed limits on each of the various OSM highway classifications. So maybe something more like “maxspeed:default:residential=25 mph”.

But I imagine there are other types of tags that might benefit from the ability to give defaults for a geographic area. So possibly it would be better to have “default:maxspeed:residential=25 mph” where and entire “default:*” namespace is created. For California something like:

“default:maxspeed = 65 mph”     // State wide maximum for all roads unless otherwise tagged or overridden by a more specific default
“default:maxspeed:primary = 55 mph”    // More specific default speed limits specific OSM road classifications
“default:maxspeed:secondary = 55 mph”
“default:maxspeed:tertiary = 55 mph”
“default:maxspeed:unclassified = 30 mph”
“default:maxspeed:residential = 30 mph”
“default:maxspeed:service = 15 mph”

> On Sep 18, 2018, at 10:15 PM, Mark Wagner <mark+osm at carnildo.com> wrote:
> . . .
> The third law: RCW 46.61.400(1).  "No person shall drive a vehicle on a
> highway at a speed greater than is reasonable and prudent under the
> conditions and having regard to the actual and potential hazards then
> existing."
> As a highway engineer pointed out to me recently, most county roads,
> especially unpaved ones, are designed around a speed limit of
> "reasonable and prudent".  The 50 MPH limit established by RCW
> 46.61.400(2)(b) simply sets a firm upper boundary; it's quite possible
> to get a speeding ticket at a lower speed.
> Sure, you can put a number on any road.  But for most rural roads
> without speed-limit signs, the number is unrelated to how fast you can
> drive on that road.

California, and I suspect most if not all other states, has a reasonable and prudent clause in the speed statutes too. So depending on conditions, especially weather conditions, theoretically you can get a speeding ticket while driving under the signed or prima facia speed limit.

However I think that is a diversionary argument that basically implies that we can’t tag any road with a speed limit because the default or signed speed limit can be trumped by a reasonable and prudent clause in the motor vehicle code.

I am a little curious about the highway engineer’s statement though. While not a civil engineer, I’ve had some interest in the field and the highway design books on my shelf (admittedly pretty old ones) all work off a design speed that is a specific number. Not a nebulous “reasonable and proper”. The design speed used to compute required sight distances, turn radii, ruling and maximum grades, etc.

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