Confusion over how TT calculates routes.

TomDavison

Hi,

I asked my TT 730T to take me from Bedford to Helston (Cornwall) avoiding motorways. It warned that there was a toll on the route, and asked if I wanted to avoid it. I said no and was given a route 310miles, taking 6hr 18min. Out of interest, I then asked it to avoid the toll, and was given an alternative that was 304miles, and 6hr 2 mins. I had always assumed that it would go first for the fastest route, avoiding motorways, but clearly it doesn't do that. Any ideas why not?

DennisN · Posted: Mon Apr 13, 2009 10:55 pm Post subject:

How interesting. I've just done the same with my 920T, using city centres and I got similar results.

Do not avoid Toll = 308, 6:14.
Avoid Toll = 301, 5:58.
_________________
Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

Andy_P · Posted: Tue Apr 14, 2009 12:49 am Post subject:

Sounds like a bug to me!!
Will pass it on...

Pocketgps · Posted: Tue Apr 14, 2009 1:21 am Post subject:

Just tried that on a TT ONE v4 - 815 map

Do not avoid Toll = 311, 6:32
Avoid Toll = 311, 6:32

The ONE v4 does not show any difference between use Toll or avoid Toll Exclamation

Shortest route = 286, 8:53

Andy_P · Posted: Tue Apr 14, 2009 2:19 am Post subject:

Are you asking it to avoid motorways first?

Oldboy · Posted: Tue Apr 14, 2009 7:11 am Post subject:

My 910 and 825 Map, going from/to City Centre doesn't even mention a Toll! Confused

It gives 6:54 hrs - 311M

But then it always overestimates the journey time. Rolling Eyes

_________________
Richard

TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120

DennisN · Posted: Tue Apr 14, 2009 7:58 am Post subject:

jpg1 · Regular Visitor Joined: Mar 20, 2009 Posts: 61

Talking of toll charge warnings, my TT Go 530 tells me there is a toll road on my route whenever I plan a journey going through the central london congestion charging zone on a Sunday afternoon! Surely it knows when the congestion charge applies and when it doesn't? Especially when there is no chance the journey being so long that I might not get into the zone until the next Monday morning...?

There doesn't seem to be any "intelligence" in the TT systems regarding when a toll charge might apply and when it clearly would not!

Thoughts anyone?

J-P

PaulB2005 · Posted: Tue Apr 14, 2009 1:14 pm Post subject:

I suspect that any toll charge data would be built into the map data, like the IQ Routes data. SO if you have the latest maps with the latest toll charges all is well. However what happens if you have maps 12-18 months out of date and the times of the toll changed? You plan a route thinking the Toll doesn't apply and end up getting fined for non-payment!

At the end of the day your Sat Nav is a GUIDE and even then primarily for navigation. Important information such as tolls and their timings should be researched separately. Just like when people had paper maps.

DennisN · Posted: Tue Apr 14, 2009 1:47 pm Post subject:

falkirk81 · Posted: Tue Apr 14, 2009 6:21 pm Post subject:

The Toll roads removal in Scotland has already been mentioned to the appropriate people. I would expect it integrated into map data sometime this year.
_________________
Tomtom GO 1005 LIVE

iPhone 12

layingback · Regular Visitor Joined: Feb 12, 2009 Posts: 124

To the original problem, my guess would be that it uses the standard (TeleAtlas?) route selection with the appropriate user-specified criteria first, and then applies IQ to the best 2, 3, 5, whatever (but a small number) of routes (TT code?). Too hard any other way :-)

And as I suspect the toll road selection is in the initial route selection (as soon as it encounters a toll), the IQ analysis never gets to consider the toll route.

On the toll direction/time, I think PaulB2005 is correct, and built into the map it just isn't refined - or current - enough to do much more than declare "toll in one or more directions some or most of the time."
_________________
Go Premium X / Go 1005

navver · Posted: Sun Apr 19, 2009 9:50 pm Post subject:

My 520 with 8.10 map shows 6.1miles 3.01 hours using the A30.
Using IQ routes surely we will all get different results unless we all use the same departure time for the journey

Andy_P · Posted: Sun Apr 19, 2009 10:00 pm Post subject:

As far as I know, if you opt for "avoid motorways" it will not use IQ routes anyway.
I think IQ routes are only used for "Fastest" calculations.

	PocketGPS
	Web