[Talk-us] braided streets

[Alan Millar]

> so I see that braided streets are 'officially' a problem
>
> http://wiki.openstreetmap.org/index.php/TIGER_fixup

Interesting.  Looking at Google Street View, it looks like these are
divided streets with an island or restriction running down the middle.  It
appears the Tiger data has separate segments for each side, with
intersection nodes where there is a break in the island.

AFAIK Tiger doesn't have the concept of ways like we do; it just has the
short segments.  I expect that our script takes Tiger segments and
assembles them into longer ways.  In this case, it appears our script
didn't know which segments went with which logical ways.

> anyone have a good way of fixing them? I'm happy to have a go in SF.

With 165 streets like that listed on the wiki, I wouldn't want to edit
them by hand myself.  And those listed are just in SF.  I suspect the
problem may exist elsewhere also.

I think deleting them and re-uploading them with the script might be
worthwhile, if there could be some more discrimination or constraints.  I
could see it being tricky, though.

I can imagine a script that goes through the two ways and identifies the
average angle of the street, and swaps node membership in the ways to
match which side it should be on.

Perhaps Dave Hansen has some insight on the Tiger upload script.

Another question is what do we want to do with the intersections?  Should
it be a single node, or two nodes?  I just dealt with this at:

http://informationfreeway.org/?lat=45.553593680216935&lon=-122.68115036884754&zoom=17&layers=B000F000F

In this case it is a split street with light rail tracks down the middle. 
I made it three nodes where the two directions of the street and the
tracks cross the perpendicular street.  Although logically it is one
intersection, I think it looks better on the map this way.

- Alan