ETA Calculation

[thad.myer]

Hello all-

I've had my 100Xl for a little over a year and never really noticed that the calculations for arrival time were completely wrong. I had always assumed that when I entered a destination, my TomTom calculated time of arrival based off the speed limits of the roads I was traveling. I noticed that it was never right, but assumed that was due to my lead foot.

Last week I was driving from Minneapolis, MN to Wausau, WI when I did the calculations myself. TomTom had my ETA based on a speed of 45 mph. This in spite of a trip that is mostly four lane highway (65+).

Can anyone explain this to me?

Is there any way to adjust this so that ETA is close to being accurate, or is this just a fatal flaw in an otherwise great product.

Thanks in advance

 

[mvl]

If you have a pre-IQroutes model (suspect 100Xl is a typo), tomtom routes based on road class, assigning fixed speeds to each road class rather than use speed limit data. It was known to grossly overestimate travel duration, and be generally worst in class in arrival time estimates.

The latest tomtoms (eg: ONE 140 / XL 340) have IQroutes, which is based on historical time-of-day/day-of-week driving speeds of tomtom owners who selected the "submit anonymous data" option.

With IQroutes, tomtom has leapfrogged all the competition, far and away (in my opinion) the best in urban arrival times and directions. However, if you have a lead foot, your highway arrival times will be off if your lead foot is faster or slower than average driver.

 

[dhn]

None IQ routing determines ETA based upon supposed speed limits of road types travelled. Some are incorrect and, for some, well, people driver faster than the posted speed; consequently, ETA is usually way overstated at the outset and slowly changes to closer to reality the longer the user is driving the route.

IQ routing, however, is more precise since it supposedly takes into account the true speed drivers are going on the roads selected for a route, regardless of speed limit. The first version of IQ routing took into consideration the day of the week drivers were travelling.

The latest version of IQ routing (referred to as IQ2) takes into consideration the TIME of day, not just the day of week, the route is being travelled. Consequently, the ETA's are usually quite realistic, right from the outset.

IQ information is a function of: the higher end map used (810 and higher where IQ info is in the map) and the models with the latest firmware to take advantage ('interpret the data') of IQ info. The Go models and new TT IQ models can deal with IQ routing.

 

[CynicX]

As posted, your unit is functioning "properly" at least in accordance to other none IQ route models. IQ routing is a HUGE improvement in not only ETA but routing (since it has more accurate reading of traveled road speeds better route selections are made) so keep that in mind if you are ever in the market for a new unit...

This is a good none bias article of Garmin vs Tomtom written by a moderator of a Garmin forum.

GpsPasSion - Reference site GPS POIs Radars

About 1/2 to 3/4 into the article IQ routing is explained a little. It seems from that and from what I've read its taking what some would consider Tomtom from having some of the worst routes to surpassing all and now having some of the best routes along with much more accurate ETA's...

Longer distances make longer ETA errors, esp if its through rural areas. I've found (having a none IQ route model) that dense city driving is more accurate when grossly over estimated due to traffic.

The ETA errors dont bother me too much because I prefer being early and hate being late. The thing I dont like is the Leeway feature, since the ETA's are so inaccurate this feature is pretty much useless too me and I keep it permanently disabled.

 

[mvl]

Be aware that the gpspassion post was testing the earliy version 1 of IQroutes.

IQrotues2 is now available to any IQroutes capable devices with map 815 or later. It adds time-of-day data to the IQroutes engine, which in my opinion furthers the lead tomtom has on directions and arrival time estimates.

However, the IQ2 engine significantly slows down the tomtom system. The screen refresh rate has significantly slowed down, and I'm sure it now noticeably lags behind the Nuvi used in the comparison.

 

[CynicX]

Thats interesting.

Do any of the Tomtom's have a faster processor/memory then the next and experience less lag (ie 140 vs 630)?

 

[sturmey]

So how do I enable IQroutes on my TomTom one new edition, or am I doomed to have my GPS think I'm and old man driving a Buick?

 

[dhn]

Don't think that model has IQ routing in its maps.

 

[sturmey]

So I'm doomed to have one of the most customizable GPS devices that can't do a basic distance/speed=time calculation. This is regretable.

It seems like it just assumes that the average speed will always be 75% of what it really is. There should be a simple fix for that, but I guess it's burried deep inside the proprietary code and not something the rest of us can access.

I shall have to speak with support about this.
Sturmey

 

[mvl]

It can do distance/speed = time.

Problem is that the speeds in pre-IQroutes devices are really poor. Do a route demo and see how fast it drives roads. The speeds it drives are the speeds it choses routes under, and on your device you'll see how bad they are.

IQroutes fixed everything for Tomtom, and they now have the best time-specific road speeds and thus the best directions engine.

You'll need a 2007 or later GO model, or a 2009 or later ONE/XL model to get IQroutes.

 

[sturmey]

It can do distance/speed = time.

Problem is that the speeds in pre-IQroutes devices are really poor. Do a route demo and see how fast it drives roads. The speeds it drives are the speeds it choses routes under, and on your device you'll see how bad they are.

IQroutes fixed everything for Tomtom, and they now have the best time-specific road speeds and thus the best directions engine.

You'll need a 2007 or later GO model, or a 2009 or later ONE/XL model to get IQroutes.

when I go into the demo, it drives at 100km the same speed that the road is marked at.
When I map a route that is 110km all highway, all marked at 100km in the TOMTOM maps it says the trip will take 1:50hr NOT 1:06hr which is what it should say.
This is with the latest updates on the TomTom home software, the latest updates on the GPS application software, and with any of the maps that I have access to including the latest update.

I spoke with support and they walked me through doing a full hard reset and downloading the latest after verifying I had the most updated Home software.
Support has no answers for ETA other than saying, try the routing software online. Which I can't access while driving.

I just need to figure out how to get the latest application that supports IQroutes. I guess it's time to do a bit of hacking.

 

[mvl]

when I go into the demo, it drives at 100km the same speed that the road is marked at.
When I map a route that is 110km all highway, all marked at 100km in the TOMTOM maps it says the trip will take 1:50hr NOT 1:06hr which is what it should say.
This is with the latest updates on the TomTom home software, the latest updates on the GPS application software, and with any of the maps that I have access to including the latest update.

I spoke with support and they walked me through doing a full hard reset and downloading the latest after verifying I had the most updated Home software.
Support has no answers for ETA other than saying, try the routing software online. Which I can't access while driving.

I just need to figure out how to get the latest application that supports IQroutes. I guess it's time to do a bit of hacking.

I forgot about one caveat to my post. If the map has a speed limit loaded for the road, the route demo will drive the speed limit instead of the embedded map speed. I assume that was a legal liability patch to prevent the Tomtom from overspeeding in its demo. For roads with speed limit info, there's no way to view the embedded map speed.