[Tagging] [Bug] calculated shortest route wrong (was: often longer than fastest route)

Ilpo Järvinen ilpo.jarvinen at helsinki.fi
Wed Apr 29 19:53:29 UTC 2015

On Wed, 29 Apr 2015, Paul Johnson wrote:

> On Wed, Apr 29, 2015 at 1:58 PM, john whelan <jwhelan0112 at gmail.com> wrote:
>       The difficulty is in many cities traffic lights are synchronised
>       in such a way that cars may have to stop at the first but there
>       after if they are travelling at or close to the speed limit they
>       will not be stopped on subsequent sets of lights when travelling
>       in a straight line.  ie there is no penalty.
> I would love to know if there's a tagging schema to hint at which direction
> the green wave rolls on a street.  Tulsa is somewhat notorious for
> reintroducing two-way traffic on streets timed for one-way, effectively
> creating a "red wave" in the direction opposite the street's previous
> one-way direction.  There's quite a few around work and I dogfood the map on
> routine trips to find hangups.  Ideally, the "red wave" direction would be
> penalized severely for cars and bicycles, and incentivized for pedestrians
> (since walking the direction as the motorist's red wave usually produces a
> pedestrian green wave (or very near to it) by coincidence in many cities).

One would have to account also time of the day/weekday/holidays etc. which 
might affect the scheduling of the traffic signals. They run with 
different programs at different times of day. Tracking all those by survey 
alone might turn out rather time consuming and error-prone, however, if 
one can get the traffic light management departments to open up their 
timing data it might be very useful for this.


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