Is the journey time on a satnav based on (a) a test drive of the route, (b) an assumption about average speeds or (c) the speed limit.
The reason I ask is that I was driving on a motorway then dual carriageway yesterday. Even driving at the speed limit (with caution
- average speed cameras), I struggled to meet the arrival time. I'm also wondering how often the arrival time is recalculated. Is it (a) continuously, (b) every mile or (c) at certain waypoints on the map?
Scott
depends what type of satnav you mean?
For google maps (and I assume paid options like tomtom) it's based on live traffic data, either crowd sourced from tracking phones, or those blue roadside cameras.
I should have said TomTom. No interactive input.
Would the same apply to TomTom without any access to traffic data? Map updates every three months.
Maybe it is just as one of my friends said - that I drive too slowly :-) He also claimed this was why the catalytic converter warning light came on.
It is probably going to depend upon the sat nav. The one built into my car seems to base its predictions upon how I drive. It usually gives a very accurate arrival time, although it took a few trips early on for it to learn. I can also watch the prediction change if I get caught up in traffic, so I assume it is continuously recalculating.
Often if I'm making a journey that is new to me I'll plot the route on Google Maps the night before, to get an idea of where I'll be going and some idea of how long it'll be. The route that the car sets is often slightly different but the journey time I find to be quite accurate, even allowing for Google knowing there is less traffic in the evening.
Scott snipped-for-privacy@gefion.myzen.co.uk> wrote
That won't work because it depends on the time of day, traffic etc.
That's not feasible either for the same reason.
Mostly, but doesn't allow for different approaches for piss stops etc.
That varies with the sat nav. I found that google maps does that very well, all the time and is very accurate with morning peak traffic jam time when running into Sydney Australia trying to catch the long distance daily train back to where I was coming from when ferrying a car for mates of mine who weren't comfortable with doing a long distance trip taking hours, thru the night with him not having had any sleep at all because the trip was a last minute decisiion because the bugger changes his mind more often than he changes his shirt and having only just been taught to drive by me.
We took longer than expected because I had never driven his car model over the route that saw road icing common in winter and had grooved concrete road surface which made me wonder if he was losing a wheel bearing and so stopped to check that.
Google maps on my iphone kept updating the arrival time at a high rate. His Nokia running Windows Phone didnt and ended up way out.
Managed to miss the train and had to twiddle my thumbs till the next one the next day because I hadn't bothered to check the layout of the massive great Sydney Central railway station to work out where the country rail platforms were or even if they had the same checkin systems airlines do.
Used the train because they were unemployed povs moving to Sydney for a decent job teaching.
We pulled up at the traffic lights outside the station with me driving with only a minute or so till train departure time. I stopped at the red light, told them that I was leaving, bailed out as I said that. Gave him a hell of a surprise but he did manage to get over the bridge to the north side of Sydney to his relos fine.
Yes with the best of them.
No.
No.
or (d) never in the case of the stupid standard satnav app on the Nokia running Windows Phone.
Scott presented the following explanation :
Mine is built in and it's predicted arrival time at the beginning always seems very accurate. If there are holdups though, it does seem to recalculate and it does have access to live holduproadwork data to aid in it's calculation.
ISTR I once had a Garmin satnav with live updates via Trafficmaster.
But nothing beats Google maps on an android phone apart from me.
Unless in London I can always beat the ETA.
my sat nav is so old lots of motorways are missing and it thinks I am going overland....tee hee....we used to kid on my 87 year old mother there was a lassie up in a stelitte with a pair of binos watching our movements....she believed us or pretended to ....
yip I use the wife with google maps on her phone....fantastic when roadworks buggered up th Newbury area a few years ago
We have Garmin ones, plus an built in one in one car.
Generally I find the predicted times very accurate.
If you deviate from the original route, get delayed, etc, they all seem to update almost instantly ( a matter of seconds).
One is in our motorhome which, being a PHGV ( and the Garmin allows for that, it is one you enter the vehicle details into so it avoids restrictions, displays the correct speed limit etc) trips take longer. It seems to allow for that.
I have a Garmin satnav, must be c 10 years old by now. I find it amazingly accurate. I always update it (via desktop) before a long trip. Two weeks ago, I drove from Dundee to Thurso - about 240 miles. I left just before 6 am, and it predicted 5 hours and 3 mins. I stopped for c 15 mins at Inverness, and the satnav eta altered accordingly. It was (or I was!) only 2-3 minutes out at journey's end.
Well many these days are updated continuously, but when you are starting they tend to make a best guess, but if traffic gets in the way, or an accident occurs on your route then often its not going to be what they say. I've noticed this increasingly on the apps that allow you to walk and use public transport, and its based on your average walking speed and the official bus timetables, which as we know tend to be a rough guide only since most roads have been narrowed to accommodate bikes. Brian
My built in one (Ford) is pretty accurate. I mostly just have it on in case of traffic problems as I know the way.
One bit that amuses me is travelling from the outskirts of Brighton to my old school (which I do once or twice a year). It wants me to go down the old A27 into the city, then keep on it to the school. Logical, but...
Starting point: 50.86015939917669, -0.0961719029189884 Ending point: 50.83406561896519, -0.15246266203871717
I don't go that way. I keep on the new A27, over the A23, then up to the top of the hill at 50.85832378793581, -0.1749081514350294, then turn left.
It looks a long way round but it isn't. As soon as I have committed to that route, the satnav says "Oh, yeah" and knocks 10-15 minutes off the arrival time.
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