[Talk-us] Freeway directions

Martijn van Exel martijnv at telenav.com
Fri Oct 18 00:34:14 UTC 2013

Thanks for all your input. For the interstates it seems to be somewhat
straightforward, at least for the two digit ones as Ian indicated. It
gets tricky when you enter the realm of three-digiters and US and
state routes... That is where explicit directionality would be

If we were to dig up a definitive resource for the cardinal directions
*as signposted* somehow, I see two ways to proceed:
1) continuing the apparently increasingly (?) popular (and to me,
sensible) creation of relations per direction and tagging each with
direction=[N|S|E|W], splitting up the rarer cases where freeways don't
have one single signposted cardinal direction.
2) tagging exising relation members consistently with role=[N|S|E|W].

I much prefer 1) but I am still not convinced I am not overlooking
another (better) mapping practice?


On Thu, Oct 17, 2013 at 1:48 PM, Saikrishna Arcot <saiarcot895 at gmail.com> wrote:
> Just to add, three-digit routes tend to be either regional or be
> loop-shaped, where the designated direction changes.
> Saikrishna Arcot
> On Thu 17 Oct 2013 03:40:07 PM EDT, Ian Dees wrote:
>> On Thu, Oct 17, 2013 at 2:31 PM, Martijn van Exel <m at rtijn.org
>> <mailto:m at rtijn.org>> wrote:
>>     Yea, I realized that as well. There's even a section of I-80 / I-580
>>     in Berkeley, CA where the directionality of I-80 and I-580 is
>>     opposite... http://goo.gl/maps/XROab (The actual compass direction is
>>     more like N/S on that stretch.)
>>     I don't know if there's a definitive reference for the 'official'
>>     directionality of the freeways?
>> I'm sure someone will pipe up with more authoritative answers, but as
>> far as I know interstates can only be east/west or north/south.
>> North/south roads are odd numbered and east/west are even.
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Martijn van Exel
OSM data specialist

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