[Tagging] Micro mapping traffic signals

[Martin Koppenhoefer]

2013/8/28 Kytömaa Lauri <lauri.kytomaa at aalto.fi>

> I won't be saying anything about the discussed
> alternatives at this time, but just wish to point
> out that "this intersection is controlled by signals"
> when used only on the intersection nodes, can't
> be straight away used as a constant time penalty
> for each such node.
>



yes, there are also other reasons: the same road will mostly have its
traffic lights coordinated, so when you get green you will often have green
for the next junctions as well (green wave
http://en.wikipedia.org/wiki/Green_wave ) if you stay on the same road,
while it is probable that you would soon get red when turning. Some routes
(e.g. to the centre) are deliberately penalized (long red, short green and
you go from one red to the next) in order to discourage drivers taking them
(to reduce traffic in certain areas). Routing algorithms would have to know
all phases of the traffic lights for a perfect result. These phases may
also change during the day or sometimes even dynamically (traffic
intensity, manual intervention, emergency and psv interaction). In
particular cases they can be remotely switched, see this video for
illustration (it is in German language for kids, but you can maybe also
understand it looking only on the images):
http://www.wdrmaus.de/sachgeschichten/sachgeschichten/sachgeschichte.php5?id=2907

cheers,
Martin
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