Hi! We see you’re using an ad-blocker. We’re fine with that and won’t stop you visiting the site.
But as we’re losing ad-revenue from this then why not make a donation towards website running costs?. Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
Joined: Nov 14, 2003 Posts: 2143 Location: Surrounded by A1, M1 & M25
Posted: Mon Nov 10, 2008 8:21 am Post subject:
My very brief experience of the HD traffic is that on the M1 and M25 it is picking up incidents that are not reported on the TMC or on TrafficTV. I noticed one particular one yesterday where a lane was closed for some repairs near Watford and the traffic was backing up but only the HD reported it.
Later on yesterday I was using the HD at home whilst exploring the functions of the unit and looking at it reporting traffic incidents on the M25 and M1 that were not being reported by other channels and on looking at the live Motorway cameras, you could see the very slow moving traffic.
One thing I did notice was that when zooming out, there were very few traffic incidents outside of the South East which made me wonder if that was just the situation or if the data downloaded is tailored for your vicinity, I hope it was just the then situation. I like to see the national picture as it can make a significant difference on a long journey such choosing between the A1 or M1 when driving from London to the North East.
At the moment of writing, HD is showing all the usual incidents around the M25 but not a single delay anywhere on the M62 corridor. RAC traffic +BBC is showing significant delays around Huddersfield and almost stationary at M62 J27 with a lane closed.
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
Posted: Mon Nov 10, 2008 8:37 am Post subject:
The data supplied is regional but the area covered is quite large, for example from Blackpool I can see down to Reading and Cardiff, but I cannot see traffic in/ around the M25.
This doesn't present a problem as I have well over two hours worth of driving time covered all around my current location as do you. But this does explain why you cannot see the M62 corridor, but then again you shouldn't need any form of traffic receiver to know that road will be heavy going at this time on a Monday morning - Mike
the level of trafic information has really picked up in the last day or so. There was always very detailed info for central London, but I see today that there is much more local info across the country.
Today my IQ route estimation was 10 minutes later than before, does it 'learn' from your own travels?
I still haven't had any traffic accurately reported. The one incident I did get reported as a 2min delay was actually more like 40 minutes. But my brain worked quicker than I'd allow time for the tomtom to sort itself out and took a different route.
The reports from others are encouraging, but i'll smile when I see it give me any for warning before I stop in traffic.
It leaves a tainted taste in my mouth when I stop in traffic for 10 minutes and the service I'm going to be paying £7.99 for shows nothing.
Currently 271. Of course, it's Friday, so more are expected, but the increase in numbers could be an indicator of improvement over the last few days, as things go live*
* no pun intended
Currently 342 - again, it could be a Monday morning thing, rather than an actual increase, but I'll post the number here anyway, for comparison.
'Normal' traffic congestion may be disabled as traffic reports will disable IQR from gathering data (well, this is what i'd do, as you don't want accidents tainting IQR data) - therefore maybe they need to differentiate congestion/accidents and maybe that is why congestion is currently not reported, but appears to be on the old tmc?
Vodaphone tracking - I'm 90% sure they will only be using Vodaphone cell data to identify delay length. It would be too difficult to use in built up areas to pin point congestion - so it makes sense to look at the flow of users. (it's unlikely all vodaphone users on a road will all begin walking in the same direction).[/b]
I still haven't had any traffic accurately reported. The one incident I did get reported as a 2min delay was actually more like 40 minutes. But my brain worked quicker than I'd allow time for the tomtom to sort itself out and took a different route.
Just curious, but if you took a different route, how do you know it was a 40 min delay?
ziro wrote:
'Normal' traffic congestion may be disabled as traffic reports will disable IQR from gathering data
Interesting theory, would you elaborate on it a little, please. IQ Routes, AFAIK, works but merely recording how long it takes to travel down particular roads or sections of road, at particular times - I don't see how having traffic information turned on could possibly affect that.
ziro wrote:
Vodaphone tracking - I'm 90% sure they will only be using Vodaphone cell data to identify delay length. It would be too difficult to use in built up areas to pin point congestion - so it makes sense to look at the flow of users. (it's unlikely all vodaphone users on a road will all begin walking in the same direction).[/b]
By definition, if the "flow" is slower than expected, there is congestion - that's precisely how this works.
Nobody is going to walk 200 miles to get to a game
(Yes, I know, off topic - sorry, couldn't resist)
EDIT (to get back on topic) - people walking from those other venues, will probably be walking in the roads anyway, until the crowd congestion clears up, so any cars stuck in amongst them will be just as slow.
True, once it thins out a bit they'll be on the pavement, but a couple of points - 1) I have found that even when the pedestrians thin out, traffic leaving a football match / other event isn't much quicker than the pedestrians and 2) I rather suspect that in the event of varying speed information, they disregard slow "traffic" when some is moving quicker to deal with precisely this issue (not to mention people who make stops along the way)
Just curious, but if you took a different route, how do you know it was a 40 min delay?
Different day. Sorry, should have explained.
Guinness2702 wrote:
Interesting theory, would you elaborate on it a little, please. IQ Routes, AFAIK, works but merely recording how long it takes to travel down particular roads or sections of road, at particular times - I don't see how having traffic information turned on could possibly affect that.
Yes, If IQ Routes is looking at the time you take to travel a road and an accident occurs - the IQ data should be discarded as the traffic was affected unexpectedly by an accident. (this is an assumption).
If that is the case, perhaps TomTom have disabled congestion from being reported through the HD traffic as an 'incident' as it will unduely affect the IQ Route data collection. (this is a theory).
Guinness2702 wrote:
By definition, if the "flow" is slower than expected, there is congestion - that's precisely how this works.
But as the poster with regards to the football matches pointed out - thats why I suggested the mobile data would be used to complement existing traffic reporting systems - it isn't accurate enough to identify cars on roads being held up as you get about a 1/2 mile radius.
But you could use it to watch people move from one cell tower triangle to the next where you know there is congestion and work out the flow rate. Else large pedestrian events would skew it.
Joined: Mar 02, 2006 Posts: 384 Location: Bedford, England
Posted: Mon Nov 10, 2008 12:10 pm Post subject:
I found an interesting? quirk with the traffic info. I was going down the A1(M) approaching Stevenage, with my shiny new 730T and had a 14 min delay showing. I didn't bother with a reroute, as this is a daily jam between J8 and J7, and I bypass it by routing through Stevenage towards Harlow instead of staying on the TT route via the motorway and J7. My arrival time on the device had been duly adjusted to allow for the delay. On that day, the traffic was worse than usual, and extended a little North of J8, so I drove through the indicated start point of the jam. As soon as I did so, the jam cleared from the display, and the 14 minute delay also disappeared from my arrival time, even though I was in the slow crawl towards J8, with stationary traffic as far as could be seen beyond the junction.
It looked like the 14 min delay was being applied to a single point on the journey at the beginning of the holdup, and that once you had passed that, it assumed no further problem, and ignored the rest of the jam.
It looked like the 14 min delay was being applied to a single point on the journey at the beginning of the holdup, and that once you had passed that, it assumed no further problem, and ignored the rest of the jam.
Is this the case?
In my experience, the delays don't just disappear by driving through them. The time to destination drops off rapidly though as you drive quickly through a long holdup that isn't there. The disappearance will have been due to an update I think. (This is with the standard traffic, not HD).
Just curious, but if you took a different route, how do you know it was a 40 min delay?
Different day. Sorry, should have explained.
Ahh, so it's a regular thing - in which case, it won't be reported as unusual traffic, as it is normal - or in your case, it was abnormal by 2 minutes, hence the 2 minute report. Remember, HD Traffic doesn't report *all* traffic, only that which is slower than IQ Routes has predicted.
ziro wrote:
Yes, If IQ Routes is looking at the time you take to travel a road and an accident occurs - the IQ data should be discarded as the traffic was affected unexpectedly by an accident. (this is an assumption).
I would expect that TT apply some intelligence to their data analysis. Using the mean of all recorded values would mean that accidents skew the average, however, using the median value, or discarding outlying values, would produce a better figure - I'm sure there are many more subtle ways in which a better value is calcuated too. I would expect that unusual traffic conditions are filtered out of the data used to generate IQ Routes information - this can then be reported when it happens in real time via HDT.
I sincerely doubt that the recording of data, and the subsequent submission of that data via HOME is disabled based on HD Traffic - hell, they probably use this data analyse real/recorded traffic flows against predicted levels to see how accurate they were and if they can improve the model. They may of course use known traffic incidents to better massge/filter the data to provide better IQ Routes data.
ziro wrote:
If that is the case, perhaps TomTom have disabled congestion from being reported through the HD traffic as an 'incident' as it will unduely affect the IQ Route data collection. (this is a theory).
As above, "normal" congestion will not be reported, as IQ Routes will have already taken that into account - remember, HDT is not used to tell you where there is slow/queueing traffic, it is used to tell you where it is *abnormally* slow, to allow your x40 to adjust your route for such abnormal conditions.
ziro wrote:
But as the poster with regards to the football matches pointed out - thats why I suggested the mobile data would be used to complement existing traffic reporting systems - it isn't accurate enough to identify cars on roads being held up as you get about a 1/2 mile radius.
But you could use it to watch people move from one cell tower triangle to the next where you know there is congestion and work out the flow rate. Else large pedestrian events would skew it.
Bottom line is you need some means to discriminate between traffic and something else .
For the most part, you can use mobile phones to detect traffic. Obviously it's not perfect and gonna get fooled at times, such as when there are an abnormal number of pedestrians about heading the same way (see also the posts elsewhere about the problems they had with, for example, trains stopping at red lights, when running parallel with motorways). Again, you could use similar statistical analysis techniques to filter the data (e.g. if some things are moving at 25mph and others at 5mph, you can probably disregard the 5mph as pedestrians, and report the speed as 25mph).
It's not gonna be perfect with current technology, but that's why you continue watch and improve the software, and have real people in the traffic control centre.
Issue 1: The 2min delay reported by the HDT was an accident, which actually took me a good 40 minutes to get the 2min marker on the map, which still said 2min when I got there. Not really what I was expecting.
Issue 2: The TT reported a usually-40-minute-on-a-clear-run journey as 40 minutes in peak time. It took me an hour and 10 minutes. However now, as a result of driving it a few times, the IQR seems to kick in a bit more accurately and has most recently revised the journey to take an hour, which is more like it.
Issue 1+2: If it has taken a couple of journeys to build up some info about my commute for IQR - the argument that "the IQR takes 'normal' congestion into account" void - since technically I'd have to drive everywhere to build up any decent IQR knowledge to get any decently predicted IQR times.
To be honest, I'd rather just see congestion/queuing traffic as a HDT report, since I am very skeptical that IQR has any existing knowledge at all.
There isn't a month of weekdays that would see the journey taking 40 minutes at peak time. IQR needed me to drive the route for a week before it got within 15 minutes of a realistic arrival time.
Now, does IQR take 'normal' congestion into account from existing data or do I need to drive every road in the country at every time of day for a week at a time before it can take 'normal' congestion into account?
If it doesn't use existing data, why can't they just display congestion (no matter how normal, since IQR doesn't take it into account) as a traffic alert?
At the moment, it seems to completely ignore 'normal' congestion.
Joined: Nov 14, 2003 Posts: 2143 Location: Surrounded by A1, M1 & M25
Posted: Mon Nov 10, 2008 3:54 pm Post subject:
mikealder wrote:
The data supplied is regional but the area covered is quite large, for example from Blackpool I can see down to Reading and Cardiff, but I cannot see traffic in/ around the M25.
This doesn't present a problem as I have well over two hours worth of driving time covered all around my current location as do you. But this does explain why you cannot see the M62 corridor, but then again you shouldn't need any form of traffic receiver to know that road will be heavy going at this time on a Monday morning - Mike
The problem with that is if you leave London and you know on the M1 150 miles north there are traffic problems, you could then decide to take the A1 North, there is little difference in distance. However if you have to go 100 miles north to (say) J19 before you find out the M1is blocked at say J27, then changing between the M1 and A1 is not a quick option.
Certainly TomTom GPRS data (TomTom Traffic) enabled you to make this decision before leaving London.
Perhaps it should be modified so when you plot a long route, it updates the traffic around the areas of the possible route?
Posted: Today Post subject: Pocket GPS Advertising
We see you’re using an ad-blocker. We’re fine with that and won’t stop you visiting the site.
Have you considered making a donation towards website running costs?. Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
Hi! We see you’re using an ad-blocker. We’re fine with that and won’t stop you visiting the site.
But as we’re losing ad-revenue from this then why not make a donation towards website running costs?. Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
Forum FAQ
Search
Usergroups
Profile
Log in for private messages
Log in
- Mike
