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uklee Occasional Visitor

Joined: Dec 07, 2006 Posts: 40
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Posted: Wed Jul 11, 2012 7:33 am Post subject: M4 closure and HD traffic |
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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.
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2216 Regular Visitor

Joined: Dec 10, 2005 Posts: 245
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Posted: Thu Jul 12, 2012 10:15 pm Post subject: |
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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. |
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technik Lifetime Member

Joined: Mar 18, 2004 Posts: 789 Location: Midlands UK
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Posted: Thu Jul 12, 2012 11:18 pm Post subject: |
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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. _________________ GO 620, Tomtom Android EU,
Garmin 2548LMT-D; 2599LMT-D |
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Andy_P Pocket GPS Moderator


Joined: Jun 04, 2005 Posts: 19991 Location: West and Southwest London
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Posted: Thu Jul 12, 2012 11:54 pm Post subject: |
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Ignoring for a minute whether it could route you round the jams or not... did it know the jams were there? _________________ "Settling in nicely" ;-) |
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Kremmen Pocket GPS Verifier


Joined: Mar 03, 2006 Posts: 7191 Location: Reading
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Posted: Fri Jul 13, 2012 6:35 am Post subject: |
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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. _________________ DashCam:
Viofo A119 V3 |
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2216 Regular Visitor

Joined: Dec 10, 2005 Posts: 245
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Posted: Fri Jul 13, 2012 8:29 am Post subject: |
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Andy_P wrote: | Ignoring for a minute whether it could route you round the jams or not... did it know the jams were there? |
Yes, on my xl live iq it did but it was everywhere, no road was free from traffic on that Tuesday. |
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matthewj Frequent Visitor

Joined: Apr 03, 2006 Posts: 751
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Posted: Fri Jul 13, 2012 11:41 am Post subject: |
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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. |
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2216 Regular Visitor

Joined: Dec 10, 2005 Posts: 245
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Posted: Fri Jul 13, 2012 3:33 pm Post subject: |
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matthewj wrote: | 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. |
I do think you have hit the nail on the head. We all moved but at such a slow rate that I was stationary 90% of the time with little bursts of movements. |
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AndyVaughan Lifetime Member

Joined: Apr 13, 2006 Posts: 1500 Location: Rossendale
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Posted: Fri Jul 13, 2012 6:49 pm Post subject: |
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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 |
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technik Lifetime Member

Joined: Mar 18, 2004 Posts: 789 Location: Midlands UK
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Posted: Fri Jul 13, 2012 7:31 pm Post subject: |
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2216 wrote: | matthewj wrote: | 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. |
I do think you have hit the nail on the head. We all moved but at such a slow rate that I was stationary 90% of the time with little bursts of movements. |
I have been past very long queues on the M40 in opposite direction, with no sign of any traffic delays shown for the stationary direction.
TomTom probably does just think there is no traffic in some circumstances. _________________ GO 620, Tomtom Android EU,
Garmin 2548LMT-D; 2599LMT-D |
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MrT Frequent Visitor

Joined: Nov 14, 2003 Posts: 2143 Location: Surrounded by A1, M1 & M25
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Posted: Mon Jul 16, 2012 9:52 am Post subject: |
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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. _________________ Drivelux |
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matthewj Frequent Visitor

Joined: Apr 03, 2006 Posts: 751
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Posted: Mon Jul 16, 2012 11:59 am Post subject: |
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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. |
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DennisN Tired Old Man


Joined: Feb 27, 2006 Posts: 14906 Location: Keynsham
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Posted: Mon Jul 16, 2012 1:43 pm Post subject: |
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matthewj wrote: | I think the general advice of "don't travel" is quite good. |
Here's one whitevanman who'll be taking that advice!! _________________ Dennis
If it tastes good - it's fattening.
Two of them are obesiting!! |
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mmm-five Occasional Visitor

Joined: Jun 02, 2006 Posts: 38
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Posted: Mon Jul 16, 2012 7:16 pm Post subject: |
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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. |
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MRCC Regular Visitor

Joined: Apr 06, 2008 Posts: 82
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Posted: Mon Jul 16, 2012 8:39 pm Post subject: |
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matthewj wrote: | 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. | i have seen instances where HD traffic is showing long delays in one lane (an exit lane or even a right/left turn lane at a junction) while the other lanes (straight on) show no delays. In that situation it must be monitoring the time it takes some of the vehicles (the ones in the exit/turn lane) to reappear on the side roads after the exit. i have also seen lots of cases where it doesn't seem to realize this and just shows no delays at all. |
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