ETA / speed-to-time calculations

[pajerry]

I've been using my TT One XL-S for about five months now. I am continually frustrated by the time calculations (call it whatever it is - ETA estimate, speed-to-time, arrival time, whatever.)

Here's my problem - the arrival time estimates are always off, sometimes as much as 1 hour. As an example, (warning - Canadian/metric units) I travel across the prairies fairly regularly. One trip I take is 95 km one way (let's round that up to 100 km). I travel at 120 km/h, so let's round that down to an average of 100 km/h to include the edge of town speed-up/slow-down, traffic, etc.

I leave at 9 am. You'd think the TT would tell me that I would be arriving in the neighbourhood of 10 am give or take. No... it tells me 11 am, or 10:35 am, or some time (always longer/slower) - enough that it makes me wonder if the thing is programmed to ... I don't know... add in a few rest stops? Calculate arrival time based on current speed minus 20 km/h?

I just don't get it. Any help or insight or even hacks would be appreciated. (Yes, I did search the forums using a few key words and only found discussions of route choice, not arrival time calculation.) Just so I'm clear here, there isn't an issue of multiple routes here. It's a straight shot along a single possible route (think prairie, road like an arrow as far as the eye can see.)

Thanks in advance,

Paul

 

[Ricochet]

I've also noticed that the unit makes a pretty poor initial ETA guess--it could often be described as "wildly inaccurate."

This is especially true for distances in excess of 30 miles, but mine seems to make corrections as the trip progresses. Of course, it's a simple matter to adjust the ETA down to the last minute as the final (possible) minute approaches...

R?

 

[dhn]

I've been using my TT One XL-S for about five months now. I am continually frustrated by the time calculations (call it whatever it is - ETA estimate, speed-to-time, arrival time, whatever.)

Here's my problem - the arrival time estimates are always off, sometimes as much as 1 hour. As an example, (warning - Canadian/metric units) I travel across the prairies fairly regularly. One trip I take is 95 km one way (let's round that up to 100 km). I travel at 120 km/h, so let's round that down to an average of 100 km/h to include the edge of town speed-up/slow-down, traffic, etc.

I leave at 9 am. You'd think the TT would tell me that I would be arriving in the neighbourhood of 10 am give or take. No... it tells me 11 am, or 10:35 am, or some time (always longer/slower) - enough that it makes me wonder if the thing is programmed to ... I don't know... add in a few rest stops? Calculate arrival time based on current speed minus 20 km/h?

I just don't get it. Any help or insight or even hacks would be appreciated. (Yes, I did search the forums using a few key words and only found discussions of route choice, not arrival time calculation.) Just so I'm clear here, there isn't an issue of multiple routes here. It's a straight shot along a single possible route (think prairie, road like an arrow as far as the eye can see.)

Thanks in advance,

Paul

Incorrect ETA's are a known issue with TomTom's and their calculating algorithms. Without going into great detail ('cuz I don't know enough ), the ETA is based upon the combination of road types selected by TomTom for a route. In North America, there are apparently only 3 road types: highway, main road and sideroad, as I understand. Each has a default (not necessarily correct) speed associated with it. So, the unit does its calculations of ETA based upon the math involved for the roads selected (e.g, 60 km driven at 80 kph [default] + 50 km driven at 60 kph, etc.). Well, that's how a ETA gets calculated. The closer to the destination, the more accurate the ETA becomes since there are fewer km (or miles) to travel using an incorrect default speed.

For European maps, my understanding is that there are 7 road types so the ETA's calculated will be more precise. Also, IQ routing in the x30 units with Navcore 8 will improve ETA calculations .... so the theory goes

 

[bbakernbay]

Sounds Like There is No Immediate Solution for Poor ETA Calculations

I'm very pleased with my TomTom One 3rd Edition except for the calculation for the Estimated Time of Arrival (ETA). I'm operating in kilometres and thought that this may be the reason for the vastly overestimated times. On a 6 or 7 hour trip on the freeways, the initial time is overestimated by several hours. Even after travelling for 4 or 5 hours, the calculation is still way too conservative. It isn't until you get down to the last 50 kilometres or 30 miles, does it get it close to being right, which by then is not too useful.

Is this a widespread problem, and if so, is a software fix likely to appear.

Otherwise, it's amazing technology for the price. It's really helped me greatly when travelling down here in South Florida, especially at night.

 

[dhn]

I replied to your query in this thread

Best not to post same question more than once here since possible solutions and feedback may be missed.

 

[eldorado]

I do also notice this ETA is off, but for me it has not been a big problem, I do see it updating the time as I get closer to the named destination, so to me it hasn't been a big problem, I always leave quite a bit early just in case, I just hate getting there at the exact time..............

 

[bbakernbay]

Here's TomTom's Customer Support Reply

Thank you for taking the time to contact TomTom Customer Support regarding the arrival time on your ONE 3rd Edition. My name is Cassie and we are always happy to help.

The estimated arrival time is not always going to be exact with the actual time it takes to get to your destination. When our programmers designed the unit, they added time for driving breaks, stop lights, speed limit, heavy traffic, etc. For example, when you navigate to your friend's house, you know that it only takes 50 minutes, but the unit is telling you 1 1/2 hours. The reason for this, is that the TomTom is putting into consideration that you are going to do things such as stop at traffic lights and/or signs, travel at slower speeds, take breaks or hit traffic, so that's how the arrival time is accumulated. When in route, the unit will adjust the arrival time as you go. We apologize for any frustration this has caused.

If you have any further questions or comments, please email or call us at 866-486-6866 Monday through Friday, 8:30 AM until 7:00 PM EST. Thanks again for writing. At TomTom we believe in showing you the way the easy way.

With Best Regards,

Cassie
TomTom Customer Support

 

[fdecaprio]

That answer sounds like a crock to me. My Garmin is always right on the money; why should they have built in things that might not happen? Goofy.

 

[DonLoughran]

That answer sounds like a crock to me. My Garmin is always right on the money; why should they have built in things that might not happen? Goofy.

I'd have to agree. My TomTom is always WAY (920T, but same problem apparently) too far out for ETA times. If the developers did work some voodoo magic estimates into their ETA calculations, then they certainly didn't take into consideration long distance, fixed speed trips.

I'm all for advancing technology, but could we please have the option of choosing between the current, fuzzy algorithm, and a simple, more instantaneously accurate division of distance remaining over current speed.

Or how about a third option: Divide distance remaining by average speed since last selecting a destination?

Thanks.

 

[cacherjoe]

I think that some of the issue may be that the GPS is calculating the ETA based on your current speed. I have seen both my Garmin and my TomTom act the same way. When I am traveling long distances (say several hours on the Trans Canada Highway) driving at a constant (or near) speed, like with the Cruise Control set, I get fairly accurate arrival times. I have noticed on both units that the arrival time stays pretty constant, within a few minutes, during most of the trip, but then as I get closer to the destination it will often adjust. Not too much, usually within 10 minutes, but enough that you notice it.

I would suggest that if you are driving at a variable speed, it will take some time for the unit to adjust, this I believe is because it is calculating based on the whole trip.

I may be off base here as it is based on what I have seen using both units on the road rather than technical knowledge.

J

 

[Barcard]

Same here. I can be driving at 70+ mph on a highway for the past hour, be 60 miles from home (59 of those miles on the same highway) and it says 90 minutes to destination. Real time to destination is about 55 minutes.

I turned off the time left and time of arrival displays to save myself the annoyance. Distance to destination is quite accurate, so I leave that on.

 

[troythepiper]

Calculating ETA

I am looking for a solution to this problem. The unit is seemingly calculating ETA by dividing kilometers (E.g. 200kms distance to travel) by miles ((E.g. 60 mph) and giving me a 3hr + driving time. I am hoping each time I get an update online, this is going to be fixed. Otherwise it is completely useless. Don't give me an estimated time based on when I might have to pee! I have a two hour drive across the prairie. It's not going to take me 3 hours going 110 km/h.
Anyone post a solution I would like to help test it or whatever.
Thanks all. Love the Tomtom,... hate the errors like this it makes. Some of my friends laugh at it for being so stupid.

 

[dhn]

The Go models with latest maps (815 or higher) and the latest applications (8.30 or higher) have what is known as IQ routing, taking into consideration 'real world' driving based on user feedback for time of day and day of week. Most often, the result is a much more realistic ETA.