Equipped with my first SatNav ever, I have used it as much as I can. But there is one thing that's annoying; and that's the arrival time. If I enter an Address and it starts guiding me, the arrival time starts at, say 10.30. But if part of the road is a motorway, the arrival time starts to reduce as soon as I'm driving on the motorway. Shouldn't this be programmed into the SatNav that a motorway normally means higher average speed...?

I can just imagine what commotion my trips stirs in the little metallic tin box in the back of the car:
"- Oi, he's at it again!
- ... wha? Is he using us again? C'mon, I worked yesterday - you clculate the arrival time this time.
- Right... donnit.... no, waitaminute! He's increasing the speed!
- Yeah, it's a motorway...didn't you take that into consideration?
- Nope. Should I?"

I wouldn't mind a more intelligent SatNav "staff" ...

Seriously, anyone knowing why...?

 

The Sat Nav does not use the speed limits of the roads to calculate your arrival time but uses your average speed. This is one reason why when you first start off it wont show you anything unless you actually drive a bit. I know this will change in due course but it may means a lot of map updates for each road type.

 

I was looking around on the sat nav DVD the other night and it looks like there's a file with the speeds used. I'll try to edit the file and see if that makes a difference.

 

Looking forward to hear how it went!

 

Turns out what I was looking out was the TMC config file:

# Created on Wed Jan 25 22:56:41 2006
[TMCLOC]
GERMANY1 = "DE", 0x1, [ 1, 1], "", "germany"
GERMANY2 = "DE", 0xd, [ 1, 1], "", "germany"
FRANCEPL = "FR", 0xf, [30,30], "", "france"
FRANCE = "FR", 0xf, [32,32], "", "france"
ITALY = "IT", 0x5, [ 1, 1], "", "italy"
UK = "GB", 0xc, [10,10], "", "uk"
SPAIN = "ES", 0xe, [17,17], "", "spain"
SWEDEN = "SE", 0xe, [33,33], "", "sweden"
HOLLAND = "NL", 0x8, [17,17], "", "holland"
DENMARK = "DK", 0x9, [ 9, 9], "", "denmark"
BELGIUM = "BE", 0x6, [ 1, 1], "", "belgium"
AUSTRIA = "AT", 0xa, [ 1, 1], "", "austria"
SWITZERLAND = "CH", 0x4, [ 9, 9], "", "swiss"
[TMCLAN]
ENGLISH = 1, "en", "english"
DUTCH = 3, "nl", "dutch"
FRENCH = 6, "fr", "french"
GERMAN = 7, "de", "german"
ITALIAN = 8, "it", "italian"
SPANISH = 10, "es", "spanish"
[ENVIRONMENT]
Version = "2.00"
TIDB_MAX_TI_ELEM = "300"
ASS_ROUTE_LENGTH_DEFAULT = "5"
ASS_ROUTE_OVER_100KM_DEFAULT = "100"
ASS_NORM_SPEED_RD_CL_MOTORWAY = "130"
ASS_NORM_SPEED_RD_CL_OTHERROAD = "80"
ASS_RDCE_SPEED_RD_CL_MOTORWAY = "6"
ASS_RDCE_SPEED_RD_CL_OTHERROAD = "20"
SEGL_NEAR_DISTANCE_NAVI = "2"
SEGL_DELAY_INC_FACTOR = "20"
SEGL_DELAY_DEC_FACTOR = "10"
SEGL_DIST_LEW = "5"
SEGL_DIST_DETOUR = "100"
SEGL_DELAY_THRESHHOLD = "10"
FIL_RADIUS_CIRCLE_SEGM = "1"
FIL_D_D1 = "50"
FIL_D_D2 = "150"
TMM_MAX_LOCATION_TABLE_ELEMENTS = "30000"
TMM_MAX_EVENT_TABLE_ELEMENTS = "1500"
TMM_MAX_SUPPINFO_TABLE_ELEMENTS = "255"
TMM_MAX_FILLER_TABLE_ELEMENTS = "220"

I've highlighted in red what I thought was worth trying to change but 130 kph is plenty high to get a realistic arrival time. So I'll keep looking.

 

Very interesting info! Looking forward to more...

 

I think there is much more to it than that. First, I can punch in a route for a 5 hour freeway trip in my garage and obtain an estimate that is accurate to within 15 minutes. This is despite the fact that my car has spent the last month driving in town at low speeds. If it merely used average speed, it would not be able to do this.

Likewise, assume that this long trip that is 80% highway in the beginning and 20% back roads at the end of the trip. At the point I get off the highway, the arrival time does not reflect an assumption that I'll continue to drive 75mph on the back roads.

It clearly takes the class of road into account in its calculations. It does use your average speed to adjust it's estimates on the fly, however.

 

I think it uses average speed for that particular stretch of road when driven by the navigation company in making the database. For example
compare google maps versus local.live.com
google used average speed of 65 on highways versus 70 for the microsoft version

I personally don't like the "arrival time" display. Would much prefer the "mins to go" display

 

What I find extremely annoying is the update time of the navigator. I.e. I know the distance (420km), I know the approx driving time (4.5h), still the navigator will initially state a arrival time which would be equivalent to 6.5h's of driving (140km of motorway). Only after approx 1h will it re-adjust and state the accurate arrival time. By that time I would have left the motorway already.

 

I just checked a journey I do fairly frequently. It's 124 miles and all but 5 miles are dual carriageway or motorway. The nav system said 2:32. That works out to very close to 50 mph which is 80 kph. Is the nav system assuming typical road speed is 80 kph?