All these GPS mapping services have a bad habit of sending folks the physically shortest route. This is frequently neither the simplest nor the most time-efficient route.
Technical comment: Most navigation systems - even back to the days of PC programs, before someone thought of creating an embedded version for (and now in) the car - boil down to a least cost route across a graph (as in the a collection nodes and arcs, not a pictorial depiction of a 2 dimensional data relationship). The trick is in correctly weighting the arcs (i.e. roads), and there is going to be some guessing due to not knowing the real conditions for a given road. So, if a road through The Loop ends up with a lower cost/weight than the freeway bypassing it, the algorithm will decide that is the lower cost and suggest that route.
Personal comment: The first time I headed up to Reno recently, I asked the GPS in my car for a route starting in Lake Elsinore (I'd chosen Lake Elsinore as a waypoint since I thought it would try to route me up I-215, which is shorter but slower than I-15). But, instead of sending me by the actually faster and shorter route up US-395, it recommended I take I-5 to Sacramento and then I-80 to Reno - about 100 miles further, and longer according to Google and AAA. And I'm pretty sure that wasn't attempting to route me around traffic, since there wasn't any traffic that would have made that route faster.
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branchandroot
no subject
Date: 2013-08-09 02:47 pm (UTC)no subject
Date: 2013-08-09 03:14 pm (UTC)Most navigation systems - even back to the days of PC programs, before someone thought of creating an embedded version for (and now in) the car - boil down to a least cost route across a graph (as in the a collection nodes and arcs, not a pictorial depiction of a 2 dimensional data relationship). The trick is in correctly weighting the arcs (i.e. roads), and there is going to be some guessing due to not knowing the real conditions for a given road. So, if a road through The Loop ends up with a lower cost/weight than the freeway bypassing it, the algorithm will decide that is the lower cost and suggest that route.
Personal comment:
The first time I headed up to Reno recently, I asked the GPS in my car for a route starting in Lake Elsinore (I'd chosen Lake Elsinore as a waypoint since I thought it would try to route me up I-215, which is shorter but slower than I-15). But, instead of sending me by the actually faster and shorter route up US-395, it recommended I take I-5 to Sacramento and then I-80 to Reno - about 100 miles further, and longer according to Google and AAA. And I'm pretty sure that wasn't attempting to route me around traffic, since there wasn't any traffic that would have made that route faster.