[Tagging] Micro mapping traffic signals

Fernando Trebien fernando.trebien at gmail.com
Wed Aug 28 22:41:13 UTC 2013

That's right, even in the best case scenario (mapping them at their
actual locations and expressing their impact on roads using
relations), we'd still end up with approximated delays for routing
which may be completely unrelated to the resulting, emerging traffic
patterns. So mapping the lights at the intersection node, or just
before at each entrance, or counting them twice or even thrice, that
is all unlikely to have a significant impact on routing and just give
birth to new "special cases" where the new "heuristic" didn't work.

However, using clever tricks is still better than nothing. If those
tricks have some relation to the expected traffic patterns, the routes
will be more like that of Google or Apple more often. And hey, no need
for an Internet connection.

I had a link (but lost it) to a system that was collecting traffic
data and assigning it to the IDs of OSM's ways in its own local
database. I could only find about Transiki now, which has shut down
long ago.

On Wed, Aug 28, 2013 at 3:20 PM, Bryce Nesbitt <bryce2 at obviously.com> wrote:
> On Wed, Aug 28, 2013 at 7:57 AM, Fernando Trebien
> <fernando.trebien at gmail.com> wrote:
>> However, routing would double count traffic lights in two-way roads
>> (as in Kytömaa's counting), though guessing the direction by proximity
>> to the intersection should be accurate here in about 99% of the cases,
>> as would be for stop signs.
> The double (or triple) count of traffic signals is something the routers
> need to model anyway.
> As has been pointed out, traffic engineering practice is to synchronize such
> lights.
> Even in places that deliberately mis-time signals to reduce flow,  three
> intersection length signals
> would be coordinated.
> We don't need to tag to the router!  The simple intersection node tagging is
> enough for good routing!
> (Google or Apple's routers have an advantage here: they don't have to count
> signals as they
> can count average travel time.)
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Fernando Trebien
+55 (51) 9962-5409

"The speed of computer chips doubles every 18 months." (Moore's law)
"The speed of software halves every 18 months." (Gates' law)

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