[pct-l] Accuracy of DeLorme Topos

[Karen Somers]

>Has anyone checked the accuracy of the trail shown on
the DeLorme maps.

>IMHO, one thing worse than no map is a map that is
way off.

 
I lost my PCT guidebook pages on a section of trail
near Sonora Pass.  All that I had for 80+ miles of PCT
were my DeLorme topos that I had, up until that point,
been using as overview information.  Unfortunately, I
discovered the hard way that they are NOT TO BE
TRUSTED.  DeLorme showed the PCT coming down to a
river valley several miles from where the PCT actually
exists upon the crest.  I was lost for two days and
the whole debacle resulted in me having to road walk a
highway for 7 miles back up to join the PCT at Sonora
Pass.

I found several places where DeLorme's accounting of
where the PCT runs over the land is WAY off base.  In
some places, it's dead-on.  But, as you stated, it is
better to have no map sometimes than an incorrect one.

Anyhow, based on my field test, I would strongly
discourage use of DeLorme's maps for use as detailed
hiking maps.  I may carry them again for an area
overview, as I enjoy seeing what the surrounding
country for several miles on either side of the trail
looks like, names of peaks, roads and such....and that
is not possible with the scale of maps used in the PCT
guidebooks.  But I will not trust them again to be
accurate about the PCT itself (well, I never really
set out to trust them, but I was forced to when I very
dumbly went out on the trail without my guidebook
pages).

BTW, same goes for the traces in Garmin's topo
software for the AT - I just field-tested it in North
Carolina a few weeks ago.  It failed, big time.  I
don't know about Garmin's PCT traces yet.

In the process of developing a trail guidebook over
the past year, I have learned a lot about mapping. 
Really, the only way to develop a map with an accurate
trace of a hiking trail is to either do old-fashioned
surveys on USGS quads (how they made the original AT
and PCT maps, from what I’ve heard) or to actually
walk the trail on the ground with a GPS unit recording
the way as you hike (which we just read has now been
done for the PCT).  DeLorme and Garmin are overlaying
unrelated sets of map data when they put the trail
traces down on their maps, which accounts for their
inaccuracy in some places.  Not to mention, they most
likely do not keep up with trail re-routes on a
regular basis, like the actual trail guidebooks' maps.

Your best bet is to stick with the PCT Guidebooks'
maps.

Nocona
PCT'04



 
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