[OSM-talk] Fwd: Speed in traffic jams/slow traffic

[marcus.wolschon at googlemail.com]

On Fri, 17 Apr 2009 12:32:03 +0200, Yann Coupin <yann at coupin.net> wrote:
> Le 17 avr. 09 à 12:07, <marcus.wolschon at googlemail.com>
> <marcus.wolschon at googlemail.com 
>  > a écrit :
> 
>> What maxspeed could I assume during a traffic-jam
>> of a given length or during reported "slow moving traffic"?
>>
>> Does anyone have some numbers here?
> 
> That's for TMC message handling? Isn't there provision for data  
> providers to give a mean speed or do you want to cover the case where  

There are messages that specify an explicit delay and there
are messages that only specify the length of the traffic jam.
Here the later are common on the air.

Also information about traffic-jams may not only come in via TMC.
I'm, trying to keep the architecture open for other plugins that
e.g. get such information from web-services or from other cars
or from the user.

> no speed is given. If so, determining the avg. speed is pretty much  
> impossible on a global scale as it's dependent of what the content  
> provider uses for threshold. I remember in Paris an urban highway  
> segment (speed-limit usually 90kph) is considered clogged if the avg.  
> speed falls under 30 kph and it keeps that state until the avg. speed  
> rise above 60 kph. But it is probably different values in some other  
> cities (or on different type of roads where those limits are not  
> adapted).

I guess a traffic jam of e.g. "5 kilometers on a lanes=2 highway=motorway"
will have a similar mean speed everywhere. If not, some gpx/nmea -tracks
should be able to disprove this assumption.

Does anyone have gps-tracks where he waited through a traffic jam?

I don't like to simply assume 0km/h = infinite delay for a traffic
jam and like 3 km/h for "slow moving traffic".

Marcus