Re: My trusted GPS failed me!

Back in the 1980s, a friend gave directions to his cottage. I took out
my topographical maps and plotted my route to his cottage (being a
cyclist, I tend to avoid highways). The topo map showed two bridges
across a river, with the second bridge closest to his cottage.

That second bridge turned out to be a set of fallen trees across the
river. So the map makers, probably using aerial photographs, probably
saw this as a bridge and made it a route on the topo maps.

Needless to say, when I got to some city way north, I realise that there
was no second bridge and turned back and got the first (and only) one.
Having a GPS would have helped if I had estinated tha lat/long of the
bridge, so while cycling, I would know once I would have gone far enough
beyond that vistual bridge to realise those trees were the "bridge" on
the map..

So even topo maps are not perfect.


And this year, I rode up to Réservoir Baskatong, north of Mont Laurier.
The topo maps I had didn't have half the roads to my cousin's place on
it. Interestingly since then, they seem to have updated that particular
map and it now shows tons of roads.

http://toporama.cits.rncan.gc.ca/images/b250k/03/031j.gif

However, I have no idea how a GPS unit would ever plot a route between
Ferme Neuve and the shore of the reservoir west of Ferme Neuve. From
that map, it isn't obvious which of those roads is the actual main road
(now paved).


Interestingly, I used my old paper topo maps and calculated approximate
lat/long based on distance from origin of the map (lower left corner)
and when riding those roads, the points I had estimated for the
intersections seemed to be within less than 200m of reality. I was quite
surprised. (at one intersection, I was about 50m from that point).
.

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