Limited speed

[MartyXB]

What is the characteristic of the route that my XL340 generates when I choose "Limited Speed" if I enter, say, 40 mph?

 

[dhn]

Supposedly tries to route you by roads with speeds imbedded in the mapping data that don't exceed the value you input.

Truckers that can't use high speed roads or motorhomers (a.k.a 'caravaners') sometimes use that option.

That said, the route is only as good as the road data the map has. and sometimes that isn't accurate .......... I know, a shock!

 

[MartyXB]

That is what I thought. I assume that if I input say 40 mph here in the Metro NY area it *should* exclude the freeway/expressway/highway network. I have for the longest time tried to find a way to have this done to avoid the *highway* network during rush hour where here in NY it is anything but *rush*. Most other GPS units based on the NAVTEQ maps avoid these roads by simply choosing their *avoid highways* option. This does not work with TomTom so an alternate option is needed.

 

[MartyXB]

Supposedly tries to route you by roads with speeds imbedded in the mapping data that don't exceed the value you input.

Truckers that can't use high speed roads or motorhomers (a.k.a 'caravaners') sometimes use that option.

That said, the route is only as good as the road data the map has. and sometimes that isn't accurate .......... I know, a shock!

That didn't work. I prepared a test route and it took me on "Belt Parkway", a road with 50 mph limit and I entered 40 mph as my limiting speed. So I ask again, just what does this routing option do?

 

[alfie67]

That didn't work. I prepared a test route and it took me on "Belt Parkway", a road with 50 mph limit and I entered 40 mph as my limiting speed. So I ask again, just what does this routing option do?

It hasn't done much for me except re-route off a faster metro highway but only for a portion of my planned route. I don't know what the criteria is, why it choses to opt off one route but not another equally fast route.

What it does do (!) is give you a recalculated ETA based on your inputted limiting speed.

 

[alfie67]

That didn't work. I prepared a test route and it took me on "Belt Parkway", a road with 50 mph limit and I entered 40 mph as my limiting speed. So I ask again, just what does this routing option do?

Supposedly tries to route you by roads with speeds imbedded in the mapping data that don't exceed the value you input.
Truckers that can't use high speed roads or motorhomers (a.k.a 'caravaners') sometimes use that option.

I agree with dhn - it does work. Do a test route from, say, Bismarck ND to Napoleon ND and use 45mph and you will be directed off the 75mph interstate route.

 

[Andy_P]

Supposedly tries to route you by roads with speeds imbedded in the mapping data that don't exceed the value you input.

That is what I thought. I assume that if I input say 40 mph here in the Metro NY area it *should* exclude the freeway/expressway/highway network.

I don't think it's as simple as that....

For a long time I've believed that the limited speed option for routing makes absolutely NO difference to the route calculated, but was only used to calculate a different final arrival time.

However, on some tests tonight, I set up a route that would normally take you along the M1 motorway in the UK( which has a normal speed limit of 70mph).

With a limited speed set of 50mph, the route still goes by the motorway, but at 40mph, it takes a different route to avoid it.
So I think that some rules for road use have been programmed into the TomTom which are not the same as the speed limit for the road.

(In the UK, there doesn't seem to be a MINIMUM speed limit for motorways, but there are prohibitions for "certain slow-moving vehicles" (such as powered mobility scooters or electric milk floats) which are banned form motorways and only allowed on +50mph roads if using a flashing amber beacon.)

 

[MartyXB]

So I think that some rules for road use have been programmed into the TomTom which are not the same as the speed limit for the road.

My gut feeling is that most of TomTom issues are database issues, ex the routing you on expressways/highways even if you chose the avoid freeways. All the other NAVTEQ products have no problems with this feature.If all major roads were correctly classifies as to roadway type and spped limit then the chosen routing option will behave in a consistent manner.