[OSM-talk] Highway access on hospital grounds

Greg Troxel gdt at lexort.com
Mon Jul 5 16:40:45 UTC 2021

Marco Rossi <mar7.lun2 at gmail.com> writes:

> Should the highways on a public hospital grounds (footways, etc) have
> access=*, maybe access=destination or access=permissive? The idea is
> to prohibit routing through a hospital that has multiple entrances,
> unless the routing destination is the hospital itself. Or are routers
> expected to avoid routing through the hospital grounds by default? I
> am not thinking about a specific router implementation, this is a
> general idea.

I think you are making a fundamental error in approaching this, by
adopting the concept of deciding how you would like routing to work and
then trying to fiddle access tags to make that come out the way you
want, somewhat disconnected from the reality of the access rules.

I think there is also a problem with your notion of "public" hospital.
In the US (which I realize you have a 95% probability of not being in,
by population), I don't even know what that means.  Most hospitals serve
the public but are nonprofit organizations and some are for-profit.
Very few are run by the government.  And, in the US, there is no general
right of access to government property, like there is for public streets.
And, I'd expect government-run hospitals to be *more* prickly about
random people being there.

Probably you have a different notion of "public hospital".  It would be
better to say what you mean rather than to rely on other people
interpeting those words.

The real question is what the access rules really are.  And the real
problem is that our tagging scheme doesn't really allow capturing the
way the world is, but only a simplfied model; we have adopted
conventions to sort of deal with this.

access=yes means that people have a *legal right of access*, so that
they cannot be told to leave.   This is true on public streets, but not
in many other places.

access=destination means that people have a legal right of access if
they are going someplace.  For many places in discussions like this,
that simply isn't true.

access=permissive means that there is no legal right, but that it's
generally known that the owner doesn't object to people being there.
However, near me that's generally used in cases where the default guess
would be private.

Let's consider a shopping center (buildings, parkings), privately
owned, with shops that intend to have the public visit and buy things.
That's not access=yes, formally.  Really it fits our permissive
definition, but we tag it as yes, because it is really really rare to be
told to leave, unless you are doing something like trying to organize
workers into a union or sell stuff out of your car etc.   But if you are
just passing through it's ok in practice.

What we don't have is "access=well_behaving_public" which means that no
one has a *right* of acess, but that the entity in control intends to
broadly allow the public as long as they behave reasonably.  So far we
leave it access=yes and pretty much nothing bad happens.

I would ask in the case of this hospital: Do they have signs that
prohibit through traffic?  If so, that seems fair to make
access=destination.  If they don't, then how do you know passing through
is prohibited/etc.?   If they don't have some sort of policy and
especially practice of hassling people why do you want to make routers
that are computing routes for *other people* not use these?

Perhaps, best practice for routers should be to give highway=service a
higher cost than regular highway types, to in general discourage using
service cutthroughs as being routes most people won't want, but not to
prohibit it.

Also, you should realize that the larger question of routing and use of
access=private is very difficult.   Most residential driveways around me
are access=private (in fact and in the db), and people usually tell
routers they can use a final segment of private.  But, they are almost
all just one way from a road to a house, and would never be chosen
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