[mkgmap-dev] Re: [PATCH v1] Re: maxspeed tag vs road_speed preset

Thu May 21 17:59:17 BST 2009

0> In article <212454.24051.qm at web28515.mail.ukl.yahoo.com>,
0> Marco Certelli <URL:mailto:marco_certelli at yahoo.it> ("Marco") wrote:

Marco> 1st: I do not know very well how to keep the answer in the same
Marco> thread...

Just follow-up in the normal way (sometimes called "group reply" or
"reply to all"), then remove the original sender from the recipients (so
that you don't annoy them by sending two copies).

Marco> I can speed on a city road at 60 km/h during night and 15 km/h
Marco> during day. ... And of course I can just imagine the endless
Marco> discussions for each road about the right value to give to an
Marco> "average_speed" tag... Much better would be to automatically
Marco> calculate an average_speed tag by using all information the OSM
Marco> DB already have: the highway type, the maxspeed tag, the number
Marco> of crosses per kilometer, the curves (radius and frequency) and
Marco> also the available GPX real speed data.

Yes - IIRC there is a Summer of Code project to collect and use gathered
speed data from GPS tracks to give realistic speed estimates.  But the Garmin
maps don't (as far as we know!) have any provision for time-dependent speeds.
So it's always going to be a very rough estimate.  Let's not get too
worked up about these details yet!