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

Paul Johnson baloo at ursamundi.org
Wed Apr 29 20:57:54 UTC 2015

On Wed, Apr 29, 2015 at 2:53 PM, Ilpo Järvinen <ilpo.jarvinen at helsinki.fi>

> 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.

For the sake of sanity, let's assume that we're talking traffic lights that
are either always on a timed pattern, which should also be reasonable for
signals that go to two or four way stops at night (and possibly during a
natural disaster).  This should reasonably handle normal operation of the
signals (even in Portland, which often has traffic lights skip a signal to
hold motorists, bicycles and sometimes even pedestrians to prevent a
conflicting movement with trams and streetcars).  The idea for this concept
would be to provide some hint that, under the usual set of circumstances,
going a specific direction on a two way street is going to really hurt.
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