>A typical city road posted 30 mph might move at 35 mph, As someone who lives in a city street with one school in the middle and one at either end posted at 40 km/h with an average traffic speed of 60 km/h and over 100 km/h from some high school kids driving to and from school I would prefer it if traffic stuck to the posted speed limits. Cars running across front lawns to avoid collisions are not unknown.
Cheerio John On 22 Aug 2017 7:23 pm, "Greg Troxel" <[email protected]> wrote: > > Richard <[email protected]> writes: > > > On Tue, Aug 22, 2017 at 10:00:07PM +0200, Martin Koppenhoefer wrote: > >> > >> > >> sent from a phone > >> > >> > On 22. Aug 2017, at 15:46, Richard <[email protected]> wrote: > >> > > >> > called differently, but this is it: > >> > https://wiki.openstreetmap.org/wiki/Key:maxspeed:practical > >> > >> > >> yes, but practical maxspeed depends a lot on your equipment and > >> capabilities, and on other people driving in front of you, so this > >> tag will probably not be very uniform around the globe. Also, some > >> people are willing to risk a speeding ticket, others don't. With > >> regard to the latter, the situation in Italy is particularly > >> ridiculous: the authorities have to sign post speed controls ;-) > >> i.e. speeding tickets are kind of rare. > > In most US states, there's a de facto limit higher than the signed limit > where there is very little risk of a ticket. I'm thinking that > maxspeed:practical should be the 50th percentile of typical time actual > speeds. > > > maxspeed:practical should take dense account or traffic jams into > > account as good as possible. So far I am not aware of any router > > evaluating time based conditional restrictions but those could be > > used to take rush hours somewhat into account. > > Agreed. Or even live traffic. But I agree with the notion that > maxspeed:practical should be a representative speed that's valid most of > the time. > > > maxspeed:practical should not have any values above the legal speed > > limit.. and if it had routers should ignore such values anyway, at > > least thats what I would expect from navigation software. > > Many years ago something like this was encouraged in the ancient > > proposal but it is no longer in the description.. if there is any > > remaining doubt I would explicitly state it in the wiki. > > This seems unreasonable. Maybe where you are people follow speed limits > (because they are enforced, or because speed limits are set by good > engineering practice instead of arbitrarily). In that case, though, > maxspeed:practical will be essentially maxspeed anyway, and that's fine. > But in Massachusetts, uncongested traffic in clear weather essentially > always travels above the speed limit, and the delta varies by road type. > A typical city road posted 30 mph might move at 35 mph, and an > Interstate posted 65 mph might move at 80 mph. But a particular road > that's almost Interstate (and correctly tagged trunk!) that is > inexplicably posted at 45 mph moves at 75 mph, because that's what all > the drivers think is the safe speed. > > A router should be answering the question "If I take this route, what > will happen" as accurately as possible, as a first step in choosing a > route with a pleasing outcome. Refusing to use a reasonable estimate of > traffic flow because it's below an arbitrary, known not to be enforced > limit, does users of the routing service a disservice. > > (I don't know what Apple maps does, but I think they use speed estimates > from other apple users and do not clamp them to speed limits. At least > it seems that way in that Apple computes routes that are in fact fast > but would be slower if speed limits were observed.) > > Computing a route based on what's known to happen is not the same thing > as encouraging speeding -- it's more like admitting that it usually > happens. And in all cases the driver is deciding how to drive. > > So: > > maxspeed:practical should be able to have higher values than maxspeed > > routers should use those values, higher or not > > and if that's not ok, then we need > > maxspeed:typical > > which is defined to be what usually happens, regardless of what anybody > thinks about it. > > Greg > > > _______________________________________________ > talk mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/talk > >
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