[Routing] Tiger Data and Routing

[David Lynch]

On Thu, Dec 4, 2008 at 01:49, Marcus Wolschon <Marcus at wolschon.biz> wrote:
> On Wed, 3 Dec 2008 17:20:55 -0600, "David Lynch" <djlynch at gmail.com> wrote:
>> Actually, this wouldn't be a bad place for the crowdsourcing mentioned
>> elsewhere on this list in the last couple days. Giving users the
>> ability to mark errors in the data and have it corrected -- without
>> requiring them to edit the underlying OSM data themselves -- wouldn't
>> be bad, and some of it could even be done automatically (though this
>> may not always be wise.)
>
> Hello.
>
> I have added a button "edit" that starts JOSM with the currently
> visible part of the map into my Navigator "Traveling Salesman"
> a long time ago.
> A button "Mark Error in Map" sounds good. What could such a button
> do?
> Create a note with a "FIXME=yes" and "node=..." and have the user enter
> a comment?

I hadn't put too much thought into any details of updating OSM, but my
thought was to work on a node-by-node basis and gather enough
information that the routing software could immediately stop giving
routes that use whatever bad direction was given, by giving them a
list of options of why it's a bad route, like

This route isn't possible because...
  ...the roads don't intersect here - one crosses over the other.
(Bans routing from the first way onto the second and vice-versa.)
  ...there are signs banning the turn. (Equivalent to a
turn-restriction relation.)
  ...there is a median strip or other barrier in the way. (If a turn
from one way onto another, bans that turn. If continuing on the same
way, ban moving in both ways from one side of the intersection to the
other. There are other movements that should be disallowed in either
case, but attempting to add them automatically could be complex.)
 ...the road I would turn/continue onto has one way traffic in the
opposite direction from this route. (Treat that part of the way as
one-way in the given direction.)
 ...the road I would turn/continue onto is private. (Place a high
enough cost on using that part of the way that it will only be used if
that is the only option.
 ...that road doesn't exist or is permanently closed. (Bans travel in
any direction on that part of the way.)
 ...cars aren't allowed there. (Bans travel for cars on that part of the way.)

It does add another layer of complexity in needing to check both the
errata and the original network, but it would allow a user to
immediately see an update when something is incorrect.

-- 
David J. Lynch
djlynch at gmail.com