[GRASS-user] slope along defined section (e.g. road, stream,)

[Tim Michelsen]

Hello,
I would like to get the slope of a defined section like a part of a river or
a road.

The only post dealing with such a idea was left unanswered:
[GRASSLIST:7280] Hazard Assessment
-
http://thread.gmane.org/gmane.comp.gis.grass.user/8702

My idea is the following:
1) define a starting vector point and a end vector point of a stream or road
section. 
2) then run a module to calculate the slope along that section
3) add the slope to the attribute table of the stream/road vector

While point 1 and 2 are quite clear to me I would ask you for hints on how to
calulate the slope as lined out in point 2.
What I am looking into would be a slope version of d.measure...

To have an idea on what one could like to do with the results:
* Get a first estimate (based on DEM resolution) on hydraulic gradients in
rivers
* assess the risk of certain roads in mountainious regions

Thanks in advance for your help.

Kind regards,
Timmie