Calculating Arrival Time

[jcman01]

I have a truck towing a boat that I often drive under the speed limit for obvious reasons. One thing I've noticed about my TomTom via 1535 is that it appears to calculate arrival time based on the speed limit of the highway that I'm on, not on my actual speed.

Therefore it isn't really accurate, and not helpful. Is there a setting by which I can make it calculate arrival time based on current speed?

Thanks for any help.

 

[dhn]

You may want to try turning off IQ routing and see if there is a difference.

 

[jcman01]

Silly me. I just googled and found that I am far from the 1st person to ask this question. Alas.

 

[canderson]

Since the device cannot predict the speed you plan to travel, nor can it understand why you are traveling under the limit (when you do so), it uses the information about average road speed (sliced and diced by day of week and time of day) to determine your likely arrival time. For many roads, your TomTom knows what a reasonable average speed might be. Depending up on your model (you don't tell us what you own, so ...) it may also be adding current traffic issues into the calculation. For roads for which nothing is known, it will use some fixed speeds based upon road type.

As dhn suggests, turning off IQRoutes may help since that will force the device to use the (normally) lower default speeds for various road types.

 

[jcman01]

It is a Via 1535, as I stated originally.

How do you like your Garmin hiking GPSs? I was thinking of hiking out in Colorado this summer, and was going to pick one up.

 

[canderson]

Positively love them. Not that keen on the Montana or newer Oregon series -- they're just a tad too big for my taste 'in the field'.

My go-to unit has been the Oregon 450 for some time now. Just about the right size for my hand and the screen is just big enough to get the job done. You can pick these up really cheap now that all of the newer units are on the market. Free topo maps are also available, so you don't need to by the "T" model to get a decent map. Check the Colorado Topo 2011 at gpsfiledepot.com. It's not hard to pull them down and load them. Toss in a decent sized uSD card, and you can keep TONS of maps on one of these things.

 

[Andy_P]

OLDER TomTom models had a "limited speed" option, where you could enter a maximum speed you were going to trasvel at.

Unfortunately.... in their wisdom, TomTom decided to remove that option from everything except their business-oriented "Truck" models, although I believe it has now been re-introduced in the new "Camper and caravan" model and maybe its there in the add-on "Camper" map for certain models too.

 

[Arno]

With IQ routes turned off is there no coordination to the Safety settings > Warn when driving faster than a set speed?

If not, it will not help in calculating the ETA but at least it may prevent someone from getting speeding tickets.

 

[canderson]

Don't confuse a) internal map data about specific road speed limits, and b) IQRoutes data about average speed along various road segments. With IQRoutes turned off, any speed limit data that exists in the map will still be displayed, and if warning of over-limit has been configured by the user, the alert will occur.

 

[Arno]

With IQRoutes turned off, any speed limit data that exists in the map will still be displayed, and if warning of over-limit has been configured by the user, the alert will occur.

That is a given.
My point was the question if the map data minus the "own choice" over limit could be used to calculate a possibly more accurate ETA.

 

[Arno]

With IQRoutes turned off, any speed limit data that exists in the map will still be displayed, and if warning of over-limit has been configured by the user, the alert will occur.

That is a given.
My point was the question if the map data minus the "own choice" over limit could be used to calculate a possibly more accurate ETA.

 

[canderson]

Ah, you're wondering if a person were to configure things to a certain maximum speed, whether that maximum would be included in the calculation for any roads whose 'map speed' was higher. Have never tried it to find out!

 

[dhn]

For what it is worth, in the time before IQ routing existed, my understanding is that if a user makes a speed change on a road using mapshares, that changed speed does NOT figure into the ETA calculations.

It is also my understanding that North American maps had 3 datapoints for calculating eta times while European maps had 7 datapoints (or road types) for determining ETA times.

For what it is worth......

 

[canderson]

Both correct. We were talking about the feature on the older models (and a rare few new ones) that allows the user to set a maximum speed for a trip. Does that maximum speed override the default map speed data (the three you mentioned) when it comes to computation of the arrival time?

 

[dhn]

That is a very good question. My gut feeling is that it would with a computed max speed limit (as compared to one changed by mapshare) but I don't know for sure.....

 

[Arno]

I had considered my suggestion about computed ETA considering max. selected speed as wishful thinking.

There is no technological reason that it could not be so but I presume that TT will use their manpower for deemed more important projects.
I don't think they could utilize part of the truck algorithm, the speed portion, as truck restrictions in different jurisdictions will also be applicable to roads with lesser than nationwide highway speeds.

 

[canderson]

With as few units as there are out there that even allow for a 'maximum speed' these days, it's kinda moot for most users, but it sure would be interesting to find out. Anyone have a 'caravan' model that could check?

 

[Arno]

I seem to be missing something. I was talking about setting a speed at an arbitrary level but below maximum permissible highway speeds.

I thought that all Nav3 devices had the ability at Safety settings to select Warn when driving faster than a set speed.

At least jcman01's Via 1535 should have it.

 

[canderson]

That only provides a warning at or above a fixed speed. I don't think that it operates in the same way as being able to set a maximum speed for the journey, though it's something any of us could test by configuring and running a demo route to see if the ETA changes.

There are units out there that allow you to set an actual maximum vehicle speed for, I believe, purposes of ETA calculation. It's designed not for arbitrary limiting, but for situations where the vehicle type itself actually imposes a maximum legal speed. This would include the 'Truck' series and the newer 'caravan' models available in Europe.

 

[Andy_P]

With as few units as there are out there that even allow for a 'maximum speed' these days, it's kinda moot for most users, but it sure would be interesting to find out. Anyone have a 'caravan' model that could check?

My trusty Go720 on v7.221 to the rescue!

That still has the "Always plan for Limited Speed" option in "Planning Preferences".

I set up a route of exactly 100 miles along the M1 motorway.

Here is the route summary and journey duration for a normal "fastest" route calculation.

And here is the same route with the maximum speed set to 50mph.

So, in those days at least, it all worked well and the ETA was worked out on the max speed you set.





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