Determining the difficulty/grade of hiking tracks/trails

[PetarTraykov]

So I have mountain trails/tracks as polylines and I want to determine their difficulty/grade: easy, medium, difficult. In order to do that I have to work with slopes and elevation. I am using ASTER SRTM for that manner. I followed these instructions but the values I'm getting for the slopes are weird (see the picture).

What am I doing wrong here? Is there any other way for me to find the difficulty of the tracks?

Thanks in advance.

[DanPatterson_Retired · Accepted solution]

how are you calculating slope?  And by the looks of your shape_length field, I suspect that you aren't using projected data but your coordinates are in decimal degrees and your elevations are in meters.  Project your file to a suitable projection so that all your positional values are in planar units.  Once you have fixed that, then make sure you decide whether to record slope as either a percentage or in degrees... 

[PetarTraykov]

Thank you! You saved me  

Do you think this is the proper method for determining the difficulty of the trails?

[DanPatterson_Retired]

definitely one way... you could also incorporate the concept of the length of a slope as well ... it will be more difficult to follow a 10 deg slope for 1 km than one that is only 10 meters.