Randomness (r_ness) wrote,

Satnav (GPS) recommendations wanted.

Anyone have any good recommendations for a satnav that doesn't send you through Harvard Square at the least provocation?

bedfull_o_books is looking for a new satnav. She has finally reached her wits end with her old Magellan unit, which seems incapable of coping effectively with Boston's street layout. It signals turns with insufficient granularity, loses track of where it is and then gets confused as to how to put one back on track, and almost invariably suffers from the Harvard Square problem*. On one memorable occasion it even insisted we were on the wrong side of the Hudson for an hour and a half of high-speed driving, solved only after we crossed to the side of the river it thought we were on.

I have problems with its parochiality. To it, roads outside the continental US are terra incognita. For me personally, this is crippling. Even my Cheetah GPS red light/speed camera warning device knows about cameras in Europe and Australasia, as well as the US and Canada. (I recommend this device, and its perpetual database update add-on, to anyone who drives in places with speed and red-light camera revenue enhancement devices.)

As it turns out, other people have asked this question. Unfortunately those threads are years old, and dead. Apparently there wasn't an easy answer to this question.

I would guess that any satnav capable of dealing with London's street layout would be able to deal with Boston. If the satnav can get me from Hanger Lane to Islington without doing something insane like sending me south of Regents Park (just to take a random example) it should be able to avoid Harvard Square.

Unfortunately, stories of antics perpetrated by drivers too slavishly following satnavs in Britain are legion. So I don't hold out great hope.

But your suggestions are welcome.

*As applied to satnavs, the Harvard Square problem is when the navigation device insists the best route to your destination is through Harvard Square. This is almost never the case, but the routing algorithms in most satnavs persist in attempting to send you through the Square rather than accept a route around it as faster.

I theorize that this is because of two factors which applied together cause the satnav to believe the best route is through the Square. First, it believes major arteries like Massachusetts Avenue, are faster than side streets like Oxford Street, based on the speed rating of the road on paper. Experienced Boston drivers know that side streets are often faster than major arteries, partly because there are fewer traffic lights, partly because major arteries are more congested more of the time, and partly because the speed limits have little relation to actual traffic speed. Thus the Boston driver penchant for rat running through side streets.

Second, satnavs underestimate the congestion in major intersections themselves. Negotiating one's way through them can be very slow because the traffic light patterns are long. These cause tailbacks, which the satnav does not account for. One extremely useful rule in Boston driving is to avoid the major intersections whenever possible. There are obvious routes avoiding major intersections (Porter, Harvard) from Arlington Center to Central Square Cambridge, for example, but your satnav will never send you that way.
Tags: travel
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