M4 closure and HD traffic

uklee · Occasional Visitor Joined: Dec 07, 2006 Posts: 40

For the past couple days I have not been impressed with the TT HD system. I was routed of the A406 Ikea in Neasden into Brentfield Road only to find I sat there for 30 mins in a mimi jam. Even in the Harlesden Acton area TT HD was not displaying any slow moving traffic when in fact there was a issue.

Lee

2216 · Regular Visitor Joined: Dec 10, 2005 Posts: 245

To be fair to TT, I went to Twickenham on Tuesday morning and the whole area was grid-locked around Brentford. I dont think any traffic system would be able to handle it. What it should have shown was dont go anywhere J3 - J2 M4 otherwise you will have major problems.

technik · Posted: Thu Jul 12, 2012 11:18 pm Post subject:

If an area is well known to be a problem then apart from building new roads, TomTom will not always have the answer.

I did have an issue on my my GO1000 which got stuck on planning an alternative route in Oxford due to traffic. This was resolved by a hard reset, and then a clear route was found.
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Andy_P · Posted: Thu Jul 12, 2012 11:54 pm Post subject:

Ignoring for a minute whether it could route you round the jams or not... did it know the jams were there?
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Kremmen · Posted: Fri Jul 13, 2012 6:35 am Post subject:

Trafficmaster are pushing out the wrong info about the M4 closure.

On my Honda built in unit with very reliable TMC RDS it is showing junctions 2 to 3 as having very heavy traffic rather than the road being closed.

On that basis the road is not totally ruled out of routeing.
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2216 · Regular Visitor Joined: Dec 10, 2005 Posts: 245

matthewj · Frequent Visitor Joined: Apr 03, 2006 Posts: 751

Hmm, I wonder if a grid-lock actually stops the HD Traffic from working properly. The whole idea is that you can detect the slow flow of traffic by mobile phone movements. And of course you have to be able to know that a phone parked or walking or in a house is not in the stats. So if the traffic is really slow, then a phone might be moving between cells too slowly to register. And if all phones in an area are moving slowly, that could mean it was unable to determine the flow to a significant level.

Just a thought. So long as there is some movement in the area, it would probably work properly.

2216 · Regular Visitor Joined: Dec 10, 2005 Posts: 245

AndyVaughan · Posted: Fri Jul 13, 2012 6:49 pm Post subject:

but isn't the mobile phone data only one of many data sources TT use nowadays?

If there were also multiple LIVE devices all powered on and stationary along a section of road you would hope the system might guess it was a traffic jam? (ignoring the data from SIM cards in phones) - or maybe TT would just think halfords had opened a new branch

technik · Posted: Fri Jul 13, 2012 7:31 pm Post subject:

MrT · Posted: Mon Jul 16, 2012 9:52 am Post subject:

I don't believe that the mobile data part of the HD Traffic could differentiate between traffic on the elevated section of the M4 and the A4 beneath it. This would require other information sources.
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matthewj · Frequent Visitor Joined: Apr 03, 2006 Posts: 751

And just to add amusement to those who already appreciate the changes for the Olympics:

The HD Traffic system will be based on stats of moving vehicles. Obviously if a phone is travelling at 300 mph it will be ignored, but if 10% of traffic is doing 60mph, and 90% is doing 20mph, then it will probably assume that there is a fair flow and not diagnose a problem. After all, if some vehicles are able to travel at the normal speed, then we can ignore the slow ones.

Good job we don't have any lanes that make some vehicles much faster while the bulk will be slowed down a lot then...

I think the general advice of "don't travel" is quite good.

DennisN · Posted: Mon Jul 16, 2012 1:43 pm Post subject:

mmm-five · Occasional Visitor Joined: Jun 02, 2006 Posts: 38

I assume that a sat-nav at home will not provide the same data as sat-nav in a car stuck in traffic, as it's likely the one at home will be switched off and not sending any updates.

So the method for TomTom to differentiate between the two states is already in place.

I finish work in London (50 yards off M4 J2) at the end of the month, and won't be back until after the olympics have finished (using a small 'o' as that's not trademarked). I'll still be working, but doing so from about 215 miles north-west of my usual location.

MRCC · Regular Visitor Joined: Apr 06, 2008 Posts: 82

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