Nav Routs Less Than Good

<div class='quotetop'>QUOTE(pruisofpa @ Jun 17 2007, 06:06 PM) [snapback]463616[/snapback]</div>

My Garmin did the same sort of thing to me in Altoona Friday although I don't have any avoidances selected. So, maybe it is just a computer problem and not a Toyota problem?

 

<div class='quotetop'>QUOTE(Tideland Prius @ Jun 18 2007, 02:33 AM) [snapback]463846[/snapback]</div>

I know the lexus nav has an "avoid uturns when planning routes" option that an be turned off. is there a similar option on the prius nav?

one trip i make a few times a year is about 3 and a half to 4 hours long (thankfully i know the route) the nav would have me travel 45 minutes out of my way to avoid a simple uturn. there is an exit off of a highway that only goes east, meaning there is no west exit from that direction on to that highway. a simple UTurn on the next exit less than a mile down that highway saves me 45 mins on my overal trip. it seems odd that the computer in the nav system can caluculate the actual fastest route. 45 minutes is an unacceptable detore and really worries me when i travel places i dont know, just how far out of the way is my nav taking me.

for those interested in the specifics. the trip i take is from maryland to northen new jersey.
The fastest route once in NJ is 95n (turnpike) to exit 11-GSParkway to 78 east, take next exit uturn 78west to 24 to 287 to 80 to destination. The nav system wants me to take 95n(turnpike) all the way up to 280 east then 80.

 

The purpose of a GPS nav system is to get you where you are going without getting lost. If you already know how to get where you are going, why are you bothering to use the nav system?

 

Once I had a bad problem with the navigation. I was told to make a legal U-Turn and take another road. I had no avoid settings. It turned out that I was on the edge of a military base. The NAV system wanted me to avoid it, even though that part of the base was OK for travel on.

 

<div class='quotetop'>QUOTE(Swanny1172 @ Jun 18 2007, 10:01 AM) [snapback]463965[/snapback]</div>

Another useful purpose of a GPS nav system is it's ability to keep you informed of estimated time of arival, or estimated time remaining, both for the entire trip as well as for individual stops along the way.

I frequently use my nav for this purpose even when I know exactly where I'm going and how best to get there.

The problem arises when the route I intend to take (the route I know is fastest or shortest) doesn't coincide with the route the nav computes. The the estimated times are far enough off to render them useless.

I can usually encourage the nav to compute the route I intend to use by looking at where it heads off in the wrong direction, and adding a waypoint somewhere beyond that point on the route I intend to take.

 

Ours does pretty well, but as Evan suggested, it worked a lot better once we changed the speed settings for the back roads. You can force routes by adding intermediate destinations (waypoints on some systems) and linking them together.

Tom

 

<div class='quotetop'>QUOTE(efusco @ Jun 18 2007, 11:50 AM) [snapback]464005[/snapback]</div>

I wish the Prius NAV system gave us a way to save these routes. We do that all the time with our marine GPS system. With the marine system, you create a bunch of waypoints, then link them together to create a route. The routes and waypoints are named and saved in the system's memory. You could do the same sort of thing with the Toyota system if there were just some way to save the routes.

Tom

 

<div class='quotetop'>QUOTE(Danny Hamilton @ Jun 18 2007, 10:39 AM) [snapback]463993[/snapback]</div>

I have used SEVERAL different GPS NAV systems, and they all seem to have the same failing. Basically, a universal system just can't be as good as a local driver at figuring out the fastest route in a given area. My NAV system habitually sends me down US101, when everyone knows that US101 is really a very long parking lot in my area. I COULD get around it by setting a preference to avoid major highways, but the every time I went somewhere else it would be a big mess. I just drive the route I want, and eventually the system figures it out.

<div class='quotetop'>QUOTE(qbee42 @ Jun 18 2007, 12:13 PM) [snapback]464073[/snapback]</div>

That seems to be the big complaint with factory NAV systems (not just Toyota's). The aftermarket guys need to go after your business with features and regular updates, while the factory systems basically rely on all of our desires for a clean, integrated install to sell the system for them.

 

<div class='quotetop'>QUOTE(Swanny1172 @ Jun 18 2007, 11:01 AM) [snapback]463965[/snapback]</div>

Because sometimes you know how to start out but not get to the final location.

For a long time a lot of nav systems didn't think that Florida's Turnpike existed and would route you up 95 and then over to get to Orlando from SE Florida. Yes, you would get there...but it would take at least two hours longer to do it that way.

For what they charge...it should work far better than it does.

 

Another reason any GPS may give you a less than optimum route is the lack of computational horsepower. The routing algorithm has to be able to give you a route in a reasonable time with limited processing power. If it analyzed every possible route it would take way too long.

While I've had my Garmin unit take me on inefficient routes, I've also had it find new tricks in parts of town I thought I new.

 

<div class='quotetop'>QUOTE(Ken S @ Jun 18 2007, 04:00 PM) [snapback]464334[/snapback]</div>

You can have it both ways.

Put in your final destination. Drive your preferred route until you get to where you want help; the nav sys will continue from there. You can suspend or resume guidance (menu button on bezel) or simply ignore guidance until you want it.