Some experience with routing on 60Csx (bicycle)

Couple weeks ago, I set out on a 3 day bike trip. The first 2 days were
over known route I had done before. The 3rd day was across New Jersey,
over roads I had never taken and the routing was fairly complex.

I had used "Road Trip" to plan those routes with various waypoints to
ensure the GPS would plot the same route as Road Trip had.

One day 1, I experimented, telling my GPS I was on a bicycle and getting
it to recalculate the route. It added 50km to a 310km day on small routes.

ETA calculations in "bicycle" mode were as useless as those in "car"
mode. My guess is that Garmin uses a fixed speed and remaining distamce
to calculate ETA. It doesn't seem to project your ETA based on your
current or average speed.


At Port Henry, I called to book a motel, and it was full. GPS's maps
came in handy because I was able to find another motel "nearby", and the
info had its phone number and address, and I was able to make this into
a waypoint and change the route to terminate at that new destination.
(I was in car mode at that point).


This worked fine, aklthough the motel owner told me the route I took was
not what he would recommedn his customers. But looking on a map, it did
seem to be the shortest.



The next morning however, the GPS and I had major fight :-)

First waypoint in route was that motel at Fort Edwards I didn't stay at.
Second waypoint was the bridge where highway 4 crosses the Hudson river
from east to west. 3rd waypoint was probably Mechanicville on western
side of the Hudson.

There was a road closure whgich prevented me from rejoining highway 4.
So I followed the "detour" signs on the road which led me to that bridge
at the second waypoint.

The GPS kept complaining I had to turn left or u-turn to use some bridge
firther north to get back onto 4. It did so right up until I had that
bridge where my 2nd waypoint was in visual sight !!! (at that point, it
realised the shortest path to that way point was to cross the bridge !).

Once this point was passed, the GPS behaved fine and stopped complaining.

However, firther south, the 9G was closed. Another detour. At that
point, I did not trust my GPS' suggestions. There was one road I could
have taken instead of the 9. That road rejoined the 9. Since I did not
know where 9G was closed, I could not trust any route that would have
brought me back to 9g.



The 3rd day proved interesting. I already knew to question my GPS's
suggestions.

I missed the first ferry to NJ, and ended up landing at Highlangs
instead of Belford.

I delete the "Belford" waypoint from the route, and added the
"Highlands" one. But it turns out the "Highlands" waypoint I had did not
precisely match the actual dock where the Seastreak ferry lands. The GPS
litterally had me running in circles !

Once I figured the way out of that small town, the GPS seemed to plot a
route, but it was not the shortest one. I stopped and slowly scrolled
the map to see if I could cut across diagonally to rejoin the roiginal
route further south. I found one. The GPS complained at every
interesection, asking me to turn left, right or u-turn.

On that route, I saw another cyclist turn on Chapel Hill Rd. I stopped,
checked out the map and found this road was actually even shorter.
Again, the GPOS asked me to u-turn. It did not see that road as a viable
alternative. It wasn't until the next interesection was the highway 50
(rejoining the original route) that the GPS accepted my route.

The rest of the day, the GPS behaved well because I did not deviate from
the route.

My conclusion is that in "follow the road" mode, if you have a route
with waypoints, it is easy to get the GPS confused. If you just tell the
GPS to goto a certain location, it proabbly works better.


In conclusion, I have learned to not trust the GPS on a bike. There are
times where it does work well, and times where it is not only unusable,
but also an annoyance. It will take more experience before I know
preciselyt when the GPS can be and cannot be trusted.


On a final note, the return trip involved some bus travel. I figured
that the GPS "ETA" estimates would be usable. It was over 10 minutes
off. (we arrived sooner than GPS predicted, probably because Buses are
allowed to exceed highway speed limits by a certain amount).

JF Mezei wrote:

It is quite of interest which kind of map you used.

worked well here


Very often road closures are made for motor vehicles. Except when there
is a bridge missing with bicycle you should be able to mange the way.
Plus: you have very little traffic on the road.

So you trust it always on a car? Hope you wont touch water instead of a
ferry some time in future. :)

Using a GPS to show you the way should always include a healthy amount
of brain 1.0

Thomas

Thomas Paulsen wrote:


Road signs never indicate whetyer bicycle can get troiugh. You just see
a big "detour" sign, not knowing where/where the blockage is. So one
cannot afford to risk it unless you have precise information.


I don't drive a car. Just a bicycle. But I have found that the GPS
behaves mnore logixally when I tell it I am a car than when I tell it I
am a bicycle.

Good old fashioned paper maps are still superior in my opinion because
you can easily see whether some side road will lead you somewhere. The
tiny screen of a GPS unit makes that long/hard/tedious.



My experience of 2 weeks ago showed me the GPS was *WAY* less trustable
than I had expected when it comes to routing along roads.

My guess is that the software has been tested/used mostly in a "goto a
single poit" mode as opposed to having complex route with many waypoints.

In "off road" mode, the unit is better at managing such a route,
realising you are moving closer to waypoint 3 so it focuses on that
waypoint instead of insisting you backtrack to waypoint 2.


I guess I have to experiement some more to get to know what can and
cannot be trusted in the "follow the road" routing.

JF Mezei wrote:

That sounds more like my old Garmin GPS-II+ which knows nothing about roads.
The manual explains that if given a route with multiple legs it picks the
leg which is nearest to the current position and navigates to the
destination of that leg.

I've been writing a (marine oriented) navigation program for my own
amusement for my PPC and have borrowed the same algorithm.

Mike.
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JF Mezei schrieb:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Depends on the point of view. For me, I like to risk it :)
E.g. see http://www.malenki.ch/Touren/08/Sommer/Galerie/16/slide_16.html
and the following picture. :)
Maybe it's also helpful to ask some locals. Spared me already some
detours.


Still you haven't answered the question which map you use. I am using
only maps from OpenStreetMap, so I can't compare with the Garmin ones
but here it is the same. At least for me, car-routing works better
then bicycle-routing since I don't like using separate bicycle lanes,
designated bicycle ways accompanying the street, let alone footways
(not matter if bicycle allowed or not)


ack