HD Traffic & Alternative Route Calculations

[MrT]

I had a different HD traffic experience on Saturday afternoon going around the M25. The road was very busy, but it was just volume of cars and virtually no lorries on the roads. There were short stretches of traffic delays being shown (J21 clockwise to J28) as traffic briefly stopped and restarted. These were short stretches of delay, they kept occuring in different places but the overall delay for my trip kept varying between 2 and 33 minutes every few minutes and some I could actually see a mile or so ahead and they were real and quickly reported.

The problem with this was that I was being offered alternative routes every few minutes but it did not show what they were. Unless I went into browse maps or view route, I had no idea where it would take me. I would have liked to see the summary screen briefly appear.

When I reached M25-J25 going to Chelmsford it recommended due to heavy delays between J27 & J28, I leave at J27, take the M11 to Harlow and the A414 to Chelmsford, a sensible alternative. However as I was going around the M25 the delays went to about 5 mins on the original route but the unit did not revert to the original route.

I was also using Traffic TV on my mobile and it showed the delays were down to 5 mins when I was at J26 so I did a manual recalculate original and TomTom agreed that staying on the M25 was the fastest route.

Needless to say as I approached J27 the ALG display appeared and TT then announced a new delay ahead and did I want the alternative route whilst also telling me to keep right. At this stage where the slip road had started and I could see lots of brake lights ahead, I just took the exit. There was not time to select the option and recalculate before the actual split.

I have set my 940 to ask if I want to reroute, as I want the final decision over where I go. I believe if I had the unit set to automatically reroute, it would have taken the alternative route, but would again not have checked if the original was faster before finally exiting the original route.

Am I correct in that once the unit has decided an alternative route it will not recalculate unless an incident occurs on the alternative route? It appears to me that if it offers me an alternative route with an extra 15 minutes due to a 30 minute holdup on the original, if that delay on the original route clears before I reach it, I will still go on the 15 minute longer alternative route.

Is there a setting I have overlooked where it will keep looking for the fastest route and retake the original if necessary?

I also noticed that the traffic bar only appeared to show the duration of the first delay, the rest had no individual duration shown apart from the total "+X mintues."
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Drivelux

[forumhound]

I've been trying to find somebody with the HD Traffic service and TrafficTV to get a comparison (before I buy a 540).

Apart from your comments here, do you think the HD Traffic is as accurate as the Traffic Master service (via TrafficTV) ?

Thanks

[MrT]

I have used TrafficMaster for many years, first on the YQ and for the past few years on TrafficTV. I used to use it on my PDA with TT GPRS traffic and have recently moved it on to my smartphone as the GPS function in it allows you to follow the map.

The TrafficMaster information is reasonably accurate but on TrafficTV it only really covers Motorways and major A trunk roads. It also does not seem to respond quickly to incidents it can be a while before incidents appear. Its advantage over HD Traffic is that you can look at a map of the whole UK when you are on a long route and see if there are delays 300 miles away, on HD Traffic it seems to concentrate on where you are. The data is there, as it can be seen on the TT Website.

The big downside the the TrafficTV is that it is a standalone application and it provides you with TrafficData which you need to interpret and analyse. It does not warn you if something occurs on your route, you need to keep looking for incidents. It also does not work out alternative routes for you or let you know the delay for your whole journey.

Another function I have used in TrafficTV is when TomToms GPRS traffic and TrafficTV report different infomation, I look at the CCTV cameras on the TrafficTV and see if there really is an incident there.

Overall I felt I needed both TrafficTV and TT GPRS traffic to get a reasonable picture of Traffic on a long journey.

However now I have HD Traffic, I have found this to be the best information to date. It covers far more roads than the other systems and hopefully will cover more. I have seen it reporting data on local B roads around where I live which are used as M25/M1 avoiding rat runs, but not all the roads, which is a concern as you do not know which roads it does not report on and could get stuck assuimg it does report on them. The data I have seen to date is far more accurate and timely than the other systems, although it is not perfect.

I have also used TT TMC traffic but I have found it can take far to long to get a signal, it does not seem to download all the incidents and I do not like aerial wires running around my windscreen. The only advantage I can see in it for me is that it is free and it works in France.

Whilst I still use my TrafficTV, I am not yet ready to ditch it and totally rely on TT HD Traffic, but in the future I may do.

I also find it interesting that the TrafficTV on the website does not show the same motorway data as TrafficTV on my mobile.

I have my TrafficTV set up to refresh at 10 minute intervals and on a 120 mile round trip this weekend it used 350KB of data, so remember to take into account your additional data costs if any.
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Drivelux

[forumhound]

Thanks for the swift reply.

I've used TrafficTV since it was called "Traffic-I" on the Palm. Didn't bother with TomTom's own (previous) Traffic service, but I may invest in the new Live service.

Thank you again for your thoughts. I will be interested to see if there is any feedback on your post.

[pushandpull]

Well I cannot speak for HD Traffic in your area as I live in the NW (Heywood, just North of Manchester). Certainly up here it appears to work very well.
.
Yesterday I did a round trip from Heywood to Pontypool.
On the journey down no holdups were reported or encountered. This was of course the day after Boxing Day and traffic was unusually light.
Coming back it reported two delays both of 20 minutes which was accurate.
Unfortunately it didn't report them until I had tagged-on to the start of the queue!
During the delay it kept updating and quoting "Delay is now X minutes, no alternative route available". (Again the delay time was accurately reported.)
If it had given more advanced warning then I expect it could have given an alternative route off, then back on to the Motorway.
.
My impression of the HD Traffic is that it is currently still under development and results are dependent on the area you are in.
.
However, I am sufficiently impressed that I will continue to subscribe to the Live Services.

.....Ken (Heywood. U.K.)
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Nobody is perfect, which is why I'm called nobody!

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[matthewj]

[MrT]

The reason why I would have liked more than just the first delay was there were a few two minute delays in front of me which I was not really interested in and after that there was a section with a large delay which was of more concern.

The amount of fluctuations whilst meaning the data was quick and more accurate was also a bit distracting, maybe a future option would be only to announce or consider reroutes for delays above X minutes. I was getting announcements and options every few minutes due to the rapidly fluctuating nature of the traffic.

Holidays certainly seem to bring the worst drivers out on to the roads.

After all the traffic avoidance on Saturday there was once thing the HD could not have made me aware of was getting stuck behind a gritting lorry with no opportunity to overtake for nearly 10 miles.
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Drivelux

[Petekk]

I have noticed this with my 540. Once TT decides to reroute you to a "faster" route it will only recalculate the route again if there is new traffic on the alternative route (i.e it will not revert back to the original route if the traffic problem ends).

The only way route this is a manual recalculate (I think minimise delays might do it). - Sees like a issue that should be addressed by tomtom.

With regard to HD Traffic, I do not think that the coverage is as great as Tomtom like to make out. I have a feeling that TT have to create some sort of profile to include a road in the system. - Hopefully coverage will improve with time - and hence the need to recalculate the original route becomes increasingly important.

i.e If you look at central london, many roads (close together) have HD traffic info with short delays (i.e 1 min etc). These areas are clearly covered. If you then look at say, Birmingham there are roads all over the city that have traffic delays (greater than then programmed into IQ Routes) but there is no mention in Tomtom. Coverage does not appear to be of the same density over the country.

A good example local to us, is a large out of town shopping centre. The place is situated on an A road, which is slow (christmas traffic, sales etc), but tomtom shows no sign of this.

[vrojohn]

I have a 940 live and only been using it for 3 days and I have to say so far so good very accurate re delays around the north circular in London but I have not had a normal working day as many are off from work until the new year
thanks John

[MrT]

For me there is one particular rat run I wish they would cover. If you are heading West (anti-clockwise) on the northern section of the M25 and you want to go to Watford or take the M1 south (toward London) there is no exit from the M25 at J21 (either direction) to the M1 southbound. You have to leave at J21a, take the old North Orbital (A405) for 3/4 mile through Bricketwood and join the M1 at J6.

This route is almost always stationary in the mornings so when avoiding traffic here a route picked by SatNav is to leave at J22 and take the B556-A5183-B462-A41/M1. However the southbound A41 is very busy at this junction and traffic cannot easily get on the roundabout (it needs traffic lights) from the B462 and a tailback of up to a mile usually builds up which can take over 30 minutes to get through.

If the Southbound M1 gets blocked or restricted south of J5, all the traffic diverts down the A41 from J5 and the tailback to join it on the B462 can go up to two miles and takes over an hour to pass. Once the queue reaches a mile, during term time it mixes with the school runs for many large rural schools (Radlett, Aldenham Elstree area) which are out of town have pupils from a 15 mile catchment area and need cars to reach which results in total chaos.

Once people then try to escape from the B462 near the A41, they end up on local roads which are very narrow old roads in deep gullies cut by carts in the past centuries with passing places and not at all suitable for large vehicles or heavy traffic.

Since getting HD traffic I have seen traffic alerts as TT have put HD traffic routes on first on the A5183, then the B556 but not yet the B462 where the major delays occur. There is hope as there are cell stations at both ends and the middle of the B462 and it is a grey coloured route on the TT Traffic maps.
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Drivelux

[matthewj]

[DennisN]

Congratulations to each and every contributor to this thread Excellent information, well presented. I don't have (and won't be getting) an x40 because I don't think it's good enough, but I did pick up on TrafficTV which I shall now go away to Google with a view to having it on my HTC Advantage (it' s got everything else including a dishwasher and shower!) as I like the idea of live CCTV on the big screen.

As for the recalculate back to original route after accepting an alternative - with earlier models, there has been quite some debate about whether Traffic monitors the original route in order to revert to it if the delay clears. Sadly, TomTom have not contributed to the debate - if only they'd say simply Yes or No. Some people swear great oaths that it does if you leave it on "Accept re-routing". I have tried my best to force myself to accept re-routing and wait for revert to original when traffic clears, but it's very difficult when I simply don't trust the traffic information enough and cannot afford to get it wrong - re-plan against a delay of 90 minutes, along a route 30 minutes faster (but 60 minutes longer than a clear original run). Far too often I have ignored the option and found the delay not to exist. Explain to my customer that I'm an hour late due to avoiding a traffic jam which didn't exist?
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Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

[MrT]

I have been experimenting with the routes by setting a route where there is a delay, watching for an alterative offered either on automatically minimise or manual and it does not revert back to the old route. If you avoid part of a route it seems to permanently mark that on the map (in pink) until you replan.

If no incidents occur on the replanned route it does not change back if the old route clears.

There must be a change on the replanned route for it to recalculate or you manually recalculate or press the minimise delays button again.

If you deviate off the alternative route it will replan. From my brief experiments it will replan the original if set to automatically minimise delays but if you have manually told it to avoid an incident it seems to take that as avoid the road where the incident was and does not clear that avoid even when the incident has cleared.

It looks like the best settings are then "ask me if I want that route" then make a decision when nearer the incident.

As to upgrading to the x40 from the x30 I would say that was not worthwhile unless you have money to burn and are a gadget freak. I went for the x40 as over a year ago I was considering a 9 series to upgrade from TT6 but then HD traffic was announced so I waited and considered the 930 plus the HD add on. I then saw the Dutch XL HD traffic and thought there would be an integrated 9 series HD traffic and waited again then the 940 came along.
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Drivelux

[MrT]

Another example of the differing traffic systems at 1pm on New Years Eve:

TrafficTV: M45 closed
TT GPRS: M45 closed
HD Traffic: Rain but no other issues on M45.
HD Traffic in web Route Planner: No issues on M45

Image from TrafficTV

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Drivelux

[Petekk]

[/quote]You have to be aware that the HD data supplied to the device is regional, and covers only the nearby area. If you are in London, you'll not get Birmingham data, and vice versa. You can check the web site to see the total available data, though even then the maps are regional.[/quote]

This is not what I am finding. Yes the websie is showing more incidents than my x40, however it is not showing me any incidents around birmingham (where I am), but excellent detailed coverage of London.

I have previously suggested that this may be due to the need of TT to create profiles to cover a road with HD traffic. As the post from MrT suggests. coverage is incresing over time. It looks like TT are concentrating on london first!

We know that TT get some of there data from Vodafone, does anyone know if the x40 reports back traffic info (over and above the fact that it has a sim card installed).

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