[talk-au] Invisible POI's

[John Henderson]

John Smith wrote:

> The other very useful thing is to tag maxspeed=* limits, although I
> noticed a couple of speed_camera tags tagged with the speed limit
> also...

On this issue, I've noticed that adding the maxspeed tag to ways does 
influence routing choice on Garmins (when they're set to use shortest 
time for routing choice).

With that in mind, I've been adding the maxspeed tag to suburban streets 
which have a classification above "residential".  Otherwise the Garmin 
assumes highway speeds for these.

In route simulation mode, my Garmin Nuvi thoughtfully shows me exactly 
what speed is being simulated as it travels the virtual route.

In fact, my Nuvi recognises only these speeds:

20 km/h
30 km/h
50 km/h
70 km/h
90 km/h
100 km/h
130 km/h

and always takes the speed up to the next step for a simulation.  So if 
maxspeed=50 or maxspeed=60, then 70 km/h is simulated.  70 and 80 get 
simulated as 90, and so on.

If I put a maximum speed into mkgmap based on highway tags, then the 
behaviour is more complicated.  Here the speed gets rounded up, but 
properly rounded so that 50 stays 50, 70 stays 70, and so on.  However, 
if a way has a specific maxspeed tag, then the speed is treated as per 
the previous paragraph.

So bizarrely, if I set up mkgmap so that the highway=unclassified and 
surface=unpaved combination means a speed of 70 km/h then the simulation 
is done at 70 km/h.  But if the unclassified unpaved way also has a 
maxspeed=70 tag, then the simulation is done at 90 km/h

John