M3 roadworks -- speed indicator freezes?

[moonseeker]

The M3 motorway near the M25 interchange, and leading to Junction 4a, is being upgraded into a "smart motorway" and has had construction works along that section for the last 2 (3?) years.

One phenomenon that I've noticed on my TomTom is that as soon as I enter the roadworks, the speed indicator settles on one speed and locks itself there. No matter how I speed up or slow down, the speed remains constant on the TomTom. When I leave the roadworks, the speed indicator reverts back to normal.

Has anybody else noticed this strange happening?

[exportman]

Do you have the tomtom speed cameras enabled. Could it be showing your average speed through the location?

[moonseeker]

That's interesting; I've never considered that as a possibility.

I'll have to some experimentation when I next drive through.

It would be rather clever if it did that. I suppose that if it knows the entry and exit location of the cameras, the time you entered, your speed on entry, and your present speed and location it could work it out. Although as I change speed, I would have expected the "average speed" to have reflected that.

Yes, indeed. That's interesting.

[justbrowsing]

[DennisN]

One of my TomToms is even "cleverer".

It shows the normal motorway speed limit 70 with one icon, it shows the average speed limit (say 50), and it shows my average speed also. On some models, it shows the average speed limit with a line either above or below (sorry, I can't remember which). That could make you think it's freezing.

However, unlike PGPSW CamerAlert on my smartphone, TomTom doesn't do the average calculation correctly - it only does the average from start to finish and doesn't recalculate at each camera (which is what CamerAlert does). So what can happen is you may (indeed often do) arrive at an average speed zone at a much lower speed due to traffic bottlenecking on the approach to the average section. So it starts with an exaggerated low speed to calculate the average from and it will need a noticeably excessive speed to bring the average up to the limit. It is therefore possible to exceed the average between two intermediate cameras even though the TT is still showing your average - from the start - as under the limit.

Rough demonstration. Enter the zone as a traffic jam at 15mph. Jam clears quite quickly so after a while you can get up to 70mph and your average displayed on the TT will creep up to say 40mph by the time you reach the next camera. Continue at 70, and drop to 50 when the average creeps up to that. By that time the third camera comes along and your average has been well over 50 since the previous camera. Kerching!
_________________
Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

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