GO730 gives up in long tunnels

[guntbert]

In my country we have several really long tunnels (over 8 km). The software gives up on extrapolating the current position and hence I get no navigation instructions towards the end of the tunnel. It calculates the current/approximate position for about 2 minutes and then it displays "Last valid GPS signal ... minutes ago..." and thats it till I leave the tunnel. Any ideas where to tweak?

 

[dhn]

Welcome to TTF.

Unfortunately the 730 does not have the same hardware/functionality of a 930 which comes with Enhanced Positioning Technology (meaning gyroscopes built into the unit) to extrapolate where the car should be moving when a gps signal is gone.

There is no tweak you can make to a 730 to get that functionality.

 

[guntbert]

where can I submit a bug report?

Thx dhn for your reply, I was aware that there is no "enhanced positioning". However I can see no reason why the software gives up after 2 minutes, so I want the TT programmers to change that. Where can I submit a bug report?

 

[dhn]

You can call Customer Support for your country, I suppose but what do you expect the programmers to do? The gps signal does not go into tunnels so the software has no real way of correctly positioning you as you move through the tunnel.

Even EPT is not 100% accurate..

 

[guntbert]

I'm not talking about any sort of accuracy - I want it to extrapolate an estimate for position and give me navigation instructions. Just like it does for the first 2 minutes (display is gray to indicate no satellite signal, but instructions and estimates are getting updated) - with the (not so farfetched) assumption that I will continue with the same speed I had shortly before the tunnel. Garmin devices have done that for years (they have other flaws )
Do I read your statement correctly that you don't know of any place for a bug report?

 

[dhn]

You are asking for an enhancement to the application. There is no place to do that in mapshare corrections. Only calling customer support with your request.

 

[guntbert]

Will do, thx for your time.

 

[steakman]

This is a most reasonable expectation for a GPS unit to do exactly as he asks. I mean what are you gonna do, make a left hand turn at an intersection within a 8 km tunnel...?? hardly. These units should have the capability to show where you are within said tunnel at any given time - given distance traveled - speed used and knowing entry/exit locations regardless of length.

On the other hand...if there are no intersections...who really cares what happens within said tunnel..you are always going to come out the other end no..??

Theo

 

[dhn]

In fact, there are tunnels with exits other than the main one. Not only in Europe but in Boston, for example.

And that functionality was on a higher end model (920 and 930) which had Enhanced Positioning Technology built in. That involves hardware, not just software.

When the gps signal is lost on a TT, it has no clue how fast you are going in the tunnel. In Europe, they can be miles long. So, even if the unit realized you were going 50 mph when you entered the tunnel, if it assumed that speed all the way through but you really slowed down to 30 mph in the tunnel, it would be way out of the real position you were in when you exited the tunnel..

 

[Arno]

In fact, there are tunnels with exits other than the main one. Not only in Europe but in Boston, for example.

The tunnel under the Mall in Washington, DC has been my bane in the pre GPS days (haven't been there since) as there is a divergent route after about a 3/4 circle, making me end up on the bridge over the Potomac, gunning for Arlington Cemetery.

As reported in another thread, the thought behind EPT is good. In practice it is very often useless if the calculated speed is interrupted by several traffic lights while driving under an elevated express way.

Maybe that one exit tunnel situation could be solved by TomTom giving coordinate locations at the end of tunnels, automatically when calculating a route, treating those locations similar to way points in an ITN.

 

[guntbert]

Just for an update:
I've put this to TomTom support and they will be talking to development (Garmin devices have been doing that extrapolation for years).

As for my rationale: of course I know when I'm at the end of the tunnel, what annoys me is that I don't even get any sort of directions for that time (like: "I don't really know where you exactly are at the moment but at the end of the tunnel take the left lane"). I cannot see any reason for calculating that approximation for 2 minutes and then *pang* nothing.

 

[Petrite]

I agree... even if there are splits in the tunnel.. you could have a manual advance feature. After the signal is lost, the screen would pop to the next driving decision ("At mile marker 2.2 stay left in the tunnel Exit ## for route ###. Press next to advance")