ETA's on Routes are WAY OFF!!!

[marty45714]

I saw someone post on this earlier, but now that the unit has been out for a while and there are more users, I wanted to post this for comment. The Estimated Time of Arrival is terrible on these units. I inititally had a Garmin Nuvi 350, which I returned after one day when I found out this unit was coming out. When using the 350, the ETA times are damn near perfect on every trip. These Go 720 units are way off though. On a 35 minute trip to work, it lists the ETA as about 45 minutes and corrects itself as I get closer. I took a 111 mile trip the other day. Its estimate was 3 hours and 20 minutes. It took me 2 hours and 30 minutes to make the trip. It's not like I took a bunch of back roads or anything. The whole trip consisted of a US route, an interstate highway and about 8 miles on a county road. TomTom definitely needs to fix this.

 

[Balthazar_B]

If you look around various GPS forums on the web, you'll find that on longer trips, TomTom is making assumptions that you'll stop for gas, etc., and is adding that into your ETA. IMHO, they should add a preference (should be pretty easy to do via a firmware update) that lets the user decide on whether ETA should be nonstop (i.e., more accurate on nonstop trips) or as they do now.

If I'm planning a long trip, I'll scope it out first with Google or Yahoo Maps to check the ETA.

 

[tundra914]

I have traffic enabled on my TT720 (my free subscription good until the end of the year). Anyway, my TT720 is normally off by a minute or two when i commute back and forth to work, 30 minute trip. I drove 3.5 hours yesterday, MD to NJ, and it was off by 5 minutes....thats pretty darn good.

 

[bilybob]

I think the problem is with the speed coding for different highways. If you live in a big city, the estimated times are ok considering the traffic etc. On the other hand, if you live in the sticks like some of us do, tomtom assumes that you will be averaging 40-45mph on a 55 zone whereas most of us drive at 64mph on 55 zone and 75-79 on the interstates which throws the arrival times way off.

I used to hear people complain about the garmin's time estimation as too aggressive but I always found it dead on. I guess bases in KS, Garmin is geared more for the people in the sticks

 

[dkoenig]

Customization

I agree about why the TomTom appears to be off on its estimates.

I think it is using predefined speeds for types of roads. Many map software programs lets you define your driving habits. It would be nice if this was an option.

Don

 

[jt_money]

i have a tomtom go910 and this is the worst part of it. for some reason when only making a 125 mile trip it says 2hours and 10 minutes. almost like it is calculating like i am driving at 60 mile an hour or so. what it needs to do is read the current speed and divide by the miles remaining. Distance = Rate x Time i mean this is basic algebra whats so hard. i really wish they would fix this.

 

[uocooper]

Ideally if you really want this fixed you'd contact both TomTom and Teleatlas about this. Using the prepare route option to travel only on a specific type of highway and then calculating the average speed from the estimated distance and time values given on the TomTom I came up with the following. On Interstate highways the average speed is 60 mph and on non interstate highways it's a mere 40 mph.

TomTom- 866-486-6866
Teleatlas- http://mapfeedback.teleatlas.com/index.htm

 

[Nauset]

It's quite clear now that the TomTom doesn't know the speed limits of various roads. I just did about 300 miles here in Minnesota today. It was a mix of Interstate and state highways. The ETA was more than an hour off in each direction, whether it calculated the route itself or used the ITN I'd made on Google Maps. The error comes from the lack of data on the state highways where the speed limit was between 55 and 65, the majority of it the latter. And many "country" roads here have the same higher limits, especially in farm country (when I first came out here 30 years ago even the country roads were 70 mph). On the other hand, if I'm around town the TomTom picks a good mix of Interstate and surface roads for the fastest route and the ETAs work out pretty well.

 

[Larry5120]

On Interstate highways the average speed is 60 mph and on non interstate highways it's a mere 40 mph.

I'll update that just a tad.

On expressway interstates (I65, I80, I94) = 60 mph
US Highways (US6, US20, US30, US41) = 40 mph
State Highways (IN331, IL113) = 30 mph

It's not just the ETA that suffers, but the routing suffers also because by not knowing the speed limits, it'll throw you on some whacky out of the way route.

TomTom...fix this! You have everything else going for you but this.

 

[ajsasr]

I'll update that just a tad.

On expressway interstates (I65, I80, I94) = 60 mph
US Highways (US6, US20, US30, US41) = 40 mph
State Highways (IN331, IL113) = 30 mph

It's not just the ETA that suffers, but the routing suffers also because by not knowing the speed limits, it'll throw you on some whacky out of the way route.

TomTom...fix this! You have everything else going for you but this.

You hit the nail on the head Larry. It's routing that suffers too. If you are calculating for the fastest route, but your "traveling" speeds are off, then you won't get the best route. But this isn't TT problem. It's Tele Atlas. Their map data is incomplete which is causing the TT routing engine to make bad assumptions. Once speed limit data is added to the maps, like it is with Navteq, I think a lot of the problems would be fixed. I wish we could get someone at Tele Atlas to address this.

 

[Larry5120]

Interesting.

TT has this mapshare thing going. If TA shows a road going one direction, we can change it to another direction. If road is closed, we can show it closed. If a POI is missing, we can add it. If a POI is in the wrong location, we can correct it.

Mapshare has a lot of potential. I really don't think it would be too tough from a programmatic point of view to simply let us define the speed limit for certain road types and have those overrides be part of the ETA calculation formula.

THAT would make the TT darn near perfect!

 

[[email protected]]

Larry,

I agree with you. I have been using laptop navigation software for over 10 years, and the software allows you to enter your own driving habits, by setting the mph of your choice on each type of street or hgwy. Alwas works fine. Seems when I have 3 miles to go to get home it gives me a eta that I could make if I walked.... well, almost

 

[ajsasr]

Interesting.

TT has this mapshare thing going. If TA shows a road going one direction, we can change it to another direction. If road is closed, we can show it closed. If a POI is missing, we can add it. If a POI is in the wrong location, we can correct it.

Mapshare has a lot of potential. I really don't think it would be too tough from a programmatic point of view to simply let us define the speed limit for certain road types and have those overrides be part of the ETA calculation formula.

THAT would make the TT darn near perfect!

That's a great idea. The whole point behind mapshare is to allow the change of some of the more dynamic aspects of travel. Speed limits change all the time. Mapshare would be a great tool for that. TT ARE YOU LISTENING???

 

[Medic]

Demo Route!

I have noticed (at least in Canada), that the following applies here:
400-series highway/Trans-Canada: 122 km/h (Speed Limits generally 100 km/h)
Regional Routes (County Highway): 58 km/h (Speed Limits generally 80 km/h)
Major Arteries: 54 km/h (Speed Limits between 40 km/h and 80 km/h)
Side Streets: 50 km/h (Speed Limit generally between 40 km/h to 60 km/h)

--Phil

 

[osidak]

just got my TT and I noticed when installing Home it asked if it could download data that showed how long it actually took to go the route

 

[nj_tt_user]

just got my TT and I noticed when installing Home it asked if it could download data that showed how long it actually took to go the route

Yeah I guess this is so they can monitor how accurate their ETA computing is amongst other things.

 

[Larry5120]

I don't think the DEMO speeds have anything to do with the ETA calculation speeds.

When I set up a route that went straight down one of our state highways, the time calculated for the ETA was based on 30 MPH. However, when I "demo'd" the route, the demo vehicle traveled at 50 MPH.

Something odd is going on here.

 

[Larry5120]

I have noticed (at least in Canada), that the following applies here:
400-series highway/Trans-Canada: 122 km/h (Speed Limits generally 100 km/h)
Regional Routes (County Highway): 58 km/h (Speed Limits generally 80 km/h)
Major Arteries: 54 km/h (Speed Limits between 40 km/h and 80 km/h)
Side Streets: 50 km/h (Speed Limit generally between 40 km/h to 60 km/h)

--Phil

I did a quick Google Earth comparison for Canada and here is what I came up with.

The route looks to be a major road from Saskatoon to Edmonton. TomTom calls this route TransCanada 16. The common name seems to be Yellowhead Highway.


Item..............Google Earth........TomTom
==============....============........=========
Distance..........498 KM..............498 KM
Travel Time.......5H 48M..............7H 32M
ETA Calc Speed....85.86 K/H...........66.1 K/H


Interestingly, when I did the TomTom Demo, the vehicle speed was 101KM/H, which is pretty darn close to the Trans Canada speed limits. (100km/h)

TT should address this issue. It's a major flaw in their software.

 

[supamart]

It's a shame that the ETA's are so bad on TT devices. I just got the TT One XL as a gift, and I'm having the same issue. I also have a really old Garmin Quest, and I was able to tweak the average driving speeds, on various types of roads, using the MapSource software on the PC. If I could do that on the TT, then I wouldn't be tempted to return it to the store.

I believe that even the new Garmin devices come with MapSource, and you should be to tweak the average driving speeds on those as well.