[Talk-us] Boston speed limit too Re: Michigan speed limit changes coming soon

Tod Fitch tod at fitchdesign.com
Sat Jan 7 19:25:34 UTC 2017

> On Jan 7, 2017, at 10:57 AM, Bill Ricker <bill.n1vux at gmail.com> wrote:
> On Sat, Jan 7, 2017 at 12:44 AM, Jack Burke <burkejf3 at gmail.com> wrote:
>> Hey, Michigan folks, keep an eye out for some speed limit changes.... [1]
> We have a different change hitting Boston as of this last week -- the
> statutory limit on *UNSIGNED* roads/streets in Boston has changed.
> Statutory limit had been the state's 30mph (thickly settled or
> business district).
> One might presume since this changes only unsigned speed, we haven't
> entered it, so nothing to change.
> But how is a router to know ?
> [1] http://www.mlive.com/news/index.ssf/2017/01/75-mph_speed_limits_officially.html
> [2] http://www.mit.edu/~jfc/ma.html

Too bad that every time someone proposes having default values based on administrative boundaries it gets shot down like this one [1] was.

Many, in fact, almost all residential streets in my state are not signed with speed limits. I think that is true in most states, but the default values definitely change with jurisdiction. If I tag them with the default legal limit when there is no signing, I run the risk that they are not updated if the law changes. And a person driving the street can’t verify the value just by looking. If I don’t tag it, then the routing software will make an assumption on what the speed is and the assumption is likely based on the part of the world the people writing the software live and very likely won’t match my area.

To the people who then say that data should be kept outside of OSM as you can’t see it on the ground: Point me to a place were a router can get a world wide set of administrative based default speed limits. To be viable for routers to use it would need to be an open geographical database. Funny, that is what OSM is supposed to be.

Makes sense to have the OSM tagging model the real world in this regard. If we had that the a local mapper could update one value on the administrative boundary and all the roads without explicit maxspeed tagging would be covered.

[1] https://lists.openstreetmap.org/pipermail/tagging/2016-October/030330.html

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