Question about Routes plotted by GPS

[tnlefty]

I received my Tom Tom 720 for Christmas and love the ease of use and the clear voice directions. In learning to use my GPS I have taken it with me to places I know the best way to go. I plot in the location and we're off. The only problem is to date, my GPS hasn't taken what I know is the best route. Even when I set it to come back home it always has me getting off at the wrong exit. Once I keep going it corrects itself and the rest of the directions are fine.

I'm planning a trip next month and I want to be comfortable with the directions I receive from the GPS.


Any suggestions?

Thanks

Barbara

 

[dhn]

I received my Tom Tom 720 for Christmas and love the ease of use and the clear voice directions. In learning to use my GPS I have taken it with me to places I know the best way to go. I plot in the location and we're off. The only problem is to date, my GPS hasn't taken what I know is the best route. Even when I set it to come back home it always has me getting off at the wrong exit. Once I keep going it corrects itself and the rest of the directions are fine.

I'm planning a trip next month and I want to be comfortable with the directions I receive from the GPS.


Any suggestions?

Thanks

Barbara

Did you pick the fastest route? The shortest route? Avoid highways?

Also, remember that the tomtom is just a tool to provide a user with the route from point A to point B and will rarely be better or even as good as local knowledge.

The important question for any GPS, not just TomTom, is whether it will get you from point A to point B when the user DOESN'T know point B's territory.

The fact that your unit rerouted you in a timely manner is a good thing.

I wouldn't worry.........

 

[tnlefty]

I have it set for fastest route.

I hadn't thought about it in that way before. I guess when you're in unknown territory the goal is to get there even if it isn't always the most direct route.

Barbara

 

[nj_tt_user]

I agree that you have to look at your GPS unit as just a tool to assist you. It will calculate what it believes is mathematically the shortest or fastest route. Meaning, if you usually take a route you believe to be the fastest or best but yet according to the TT is .1 mile or 1 minute longer, it will use the shorter or less time consuming route which may technically be getting off that exit you usually don't. The route you usually take could simply be .1 mile longer according to its actual distance on the map causing the TT to use another "shorter" route.

 

[SShadow]

Normally I would agree with you, but to get to my home from the city, you can take two routes. One via a 50km/h route and another that is 110km/h. The difference in distance is 1km (approx). The GPS will always route me along the 50km/h stretch and then put me on the highway just before the city, instead of putting me on the highway the entire way.
But what's even funkier, is tonight I was testing a route for another user and it actually routed me onto the highway. Now, the only difference in the routes is where Hwy 103 ends it splits in two, one route goes 102 north and the other 102 south. South takes you into the city and north takes you out of the city. The route was taking me on the 102 north... But just before the 103 splits, is the entrance from the 50km/h road that it usually routes me on... LOL
So basically, it routes me along the slower route if I am going into the city, and routes me along the faster route, if I am going out of the city (northbound). Both routes have no "modifiers" - ie avoid tolls/highways/etc. So while the GPS is smart - most of the time - sometimes it can be pretty dumb.

 

[canderson]

I received my Tom Tom 720 for Christmas and love the ease of use and the clear voice directions. In learning to use my GPS I have taken it with me to places I know the best way to go. I plot in the location and we're off. The only problem is to date, my GPS hasn't taken what I know is the best route. Even when I set it to come back home it always has me getting off at the wrong exit. Once I keep going it corrects itself and the rest of the directions are fine.

I'm planning a trip next month and I want to be comfortable with the directions I receive from the GPS.


Any suggestions?

Thanks

Barbara

Unless it is still unaware of a particular road location, the 720 will pretty unerringly produce a good "least distance" route for you. However, you and others have correctly noted that "shortest time" routing is a bit of a crap shoot at times.


It's a common misconception that these devices know more than they really know about local conditions.

Speed Limits: The 720, in particular, is a bit clueless about actual speed limits. It will make some very basic assumptions about the type of a road that it has for its options, and will assign one of three speeds to it on that basis. That means that a road type (e.g., an interstate highway) that might have a 55mph limit in one place might have a 75mph limit in another part of the country -- missing the reality by a good bit. Unlike Europe, where TT seems to be far more specific about actual road speeds, TT makes these assumptions for all North American roads. With only three basic road categories (but in many cases taking into account when they are obviously within a city), attempting to create a "best speed" routing is a bit of a problem.

Traffic Lights: There can be no doubt that the traffic light conditions vary WIDELY between locations. Some cities synchronize their lights to try to keep the traffic flowing better, and some refuse to do so. Some roads have far more traffic lights per mile than others. The 720 knows nothing of any of this. It will route based upon an assumed average speed for one of its 3 road types, not knowing what specific obstacles have been thrown in the driver's way in the way of traffic control.

Those two elements alone can produce some pretty humorous routing when requesting "shortest time" routes!

 

[tomlouie]

I'm planning a trip next month and I want to be comfortable with the directions I receive from the GPS.

I would suggest sitting down at home with the unit and using the "Advanced Planning" (or "Plan Route") feature to get a feel for the types of routes it'll suggest from point A to point B. After it generates the route, look at the route details, either as text or as turn by turn images. This let's you familarize yourself with the general route so you have an idea ahead of time.

Like others have said, the GPS is just an aid, not an autopilot. You're still the driver and may have to treat what the GPS with some healthy skepticism. The GPS may give inaccurate instructions, like a turn that no longer exists or a two way street that is now only one way.

It'll help with most of the general navigation, but the fine details are still in your hands.

 

[SShadow]

I submitted my findings to TomTom.com's Map Feedback... I do not drive like my mother-in-law... I perfectly capable of making left hand turns!