Speed

IanRimmer · Posted: Thu Jan 15, 2004 7:02 pm Post subject: Speed

Just wondering what speed settings people use for the road options in tom tom ie international road/local road and so on.....

Thanks

Ian

lbendlin · Posted: Thu Jan 15, 2004 9:04 pm Post subject:

here's a suggestion that we got from TomTom a while back (in miles)

Road type...................Speed set 1..........Speed set 2
Freeway............................60..........................60
International road...............45..........................45
Major road.........................45..........................45
Secondary road................40..........................40
Connecting road............... 33..........................35
Important local road...........37..........................35
Local road.........................30..........................30
Destination road................25..........................20

Eventually it is up to you to define your own settings. Whatever works best for you...
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IanRimmer · Posted: Fri Jan 16, 2004 8:38 am Post subject:

Thanx for the reply would these work in the UK and what dfference do they make

cheers Smile

hornist · Posted: Fri Jan 16, 2004 12:02 pm Post subject:

I find the UK default ones remarkably accurate for most journeys I do, and would be very wary about fiddling with them. At first glance the figures look low, and there is a temptation to raise them - "I'm sure I drive faster than that on a motorway". Well, you do when the road is clear, but you don't if there are queues, and the 'average' figures take account of a mix of open road and slower traffic.

There are situations when they will be wrong: for example motorway driving late at night when the roads are empty, or long stretches of road that have a speed limit which is not typical for the type of raod and which TT doesn't know about.

But these are exceptions. In 'normal' driving I almost always arrive within 5 minutes of the initally predicted time for journeys of 2 - 2.5 hours, and sometimes I've arrived exactly on time. I think that's pretty good! I certianly wouldn't fiddle with the values.

Paul

psionman · Posted: Fri Jan 16, 2004 2:11 pm Post subject:

I've just tried a couple of (longish) journies - 1 to 2 hours, and I agree that the predicted time is faily good. I also agree that traffic conditions (in the UK that means CONGESTION) have a big effect.

I'm interested in the algorithm used by TomTom to calculate ETA. Does it just used the sum of miles left / set speed for each road type, or does take account of your current speed over the last so many minutes? I had a computer on my last car that worked that way

IanRimmer · Posted: Fri Jan 16, 2004 2:42 pm Post subject:

Thanx for that your right figures did seem low so i upped them to 70mph for motorways and so on but have not done any long distance driving with this yet ....think ill reset them to normal

Cheers Ian

Robin2 · Posted: Fri Jan 16, 2004 4:32 pm Post subject:

The main significance of the speeds you set is in selecting the quickest route. If you set motorway speeds a lot faster than other roads, TomTom will take you a long way round to maximise the amount of motorway used. I find fine-tuning the speeds a useful way of making TomTom choose the sort of route I prefer. I have chosen 63,62,53,47,40,34,20,15
The time to destination is just a mathematical calculation based on the roads left until you arrive and the speed you have set for each type of road. It takes no account of the speed you are actually driving at.
Robin

hornist · Posted: Fri Jan 16, 2004 4:32 pm Post subject:

anarchy-inc · Posted: Sat Jun 19, 2004 12:18 am Post subject:

SteveW · Posted: Sat Jun 19, 2004 12:41 am Post subject:

Morty · Occasional Visitor Joined: Nov 01, 2003 Posts: 10

This reply goes of at a slight tangent but it may interest you.
My last company car completed 86,000 miles in three years with an average speed of 48 mph. That includes a hellva lot of motor way miles.
TT2 arrival time was normally within 5 mins each way and it did update it self reguarly as I often kept an eye on it.
My current car 7 months old 18.000 miles has an average speed of 56 mph
And again TT2 arrival is usually within 5 mins each way.
Just to make things clear the arrival time was checked when starting and I am only counting journeys with out major hold ups.
The average speed of my first car was never reset during the 3 year period that I drove it.
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