[LINK] car computers

Scott Howard scott at doc.net.au
Tue Jan 20 11:05:32 AEDT 2009

On Mon, Jan 19, 2009 at 3:47 PM, David Lochrin <dlochrin at d2.net.au> wrote:

> Re a similar technology, I now always double check <whereis.com.au>
> directions by reference to the road map (preferably Google Maps :-).  And I
> don't understand why this application seems so prone to give less than best
> route - is it the map data or the algorithm?

Many (all?) of the maps for Australia seem to lack "speed" data for anything
but major roads, which means that the routing application isn't able to make
an optimal decision between roads.

By contrast, the mapping data for the US (or at least around San Francisco)
includes at least one speed (the speed limit) and frequently two (the
"expected" speed) for most/all road, which allows for a much more optimal
routing.  Increasingly they are also starting to include time-of-day based
speeds (65mph, except during peak hours when it's 35mph) as well as access
to live traffic data which allows even better routing.

When I was in Sydney I found that my GPS was only useful for "last mile"
routing - I very rarely used the route it gave me for getting to a
particular suburb as I almost always knew a better route, and I would only
use it to get me to the actual address through local streets which I didn't


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